Store List of Fields in Segment

Fiels may be encoded in the columnar storage or in the inverted index
for JSON fields.
Add a new Segment file that contains the list of fields (schema +
encoded)

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "tantivy"
-version = "0.21.0"
+version = "0.22.0-dev"
 authors = ["Paul Masurel <paul.masurel@gmail.com>"]
 license = "MIT"
 categories = ["database-implementations", "data-structures"]
@@ -22,10 +22,10 @@ crc32fast = "1.3.2"
 once_cell = "1.10.0"
 regex = { version = "1.5.5", default-features = false, features = ["std", "unicode"] }
 aho-corasick = "1.0"
-tantivy-fst = "0.4.0"
+tantivy-fst = "0.5"
 memmap2 = { version = "0.9.0", optional = true }
 lz4_flex = { version = "0.11", default-features = false, optional = true }
-zstd = { version = "0.13", optional = true, default-features = false }
+zstd = { version = "0.13", default-features = false }
 tempfile = { version = "3.3.0", optional = true }
 log = "0.4.16"
 serde = { version = "1.0.136", features = ["derive"] }
@@ -37,21 +37,19 @@ uuid = { version = "1.0.0", features = ["v4", "serde"] }
 crossbeam-channel = "0.5.4"
 rust-stemmers = "1.2.0"
 downcast-rs = "1.2.0"
-bitpacking = { git = "https://github.com/quickwit-oss/bitpacking", rev = "f730b75", default-features = false, features = ["bitpacker4x"] }
+bitpacking = { version = "0.9.2", default-features = false, features = ["bitpacker4x"] }
 census = "0.4.0"
 rustc-hash = "1.1.0"
 thiserror = "1.0.30"
 htmlescape = "0.3.1"
 fail = { version = "0.5.0", optional = true }
-murmurhash32 = "0.3.0"
 time = { version = "0.3.10", features = ["serde-well-known"] }
 smallvec = "1.8.0"
 rayon = "1.5.2"
 lru = "0.12.0"
 fastdivide = "0.4.0"
-itertools = "0.11.0"
+itertools = "0.12.0"
 measure_time = "0.8.2"
-async-trait = "0.1.53"
 arc-swap = "1.5.0"
 
 columnar = { version= "0.2", path="./columnar", package ="tantivy-columnar" }
@@ -75,15 +73,13 @@ matches = "0.1.9"
 pretty_assertions = "1.2.1"
 proptest = "1.0.0"
 test-log = "0.2.10"
-env_logger = "0.10.0"
 futures = "0.3.21"
 paste = "1.0.11"
 more-asserts = "0.3.1"
 rand_distr = "0.4.3"
 
 [target.'cfg(not(windows))'.dev-dependencies]
-criterion = "0.5"
-pprof = { git = "https://github.com/PSeitz/pprof-rs/", rev = "53af24b", features = ["flamegraph", "criterion"] } # temp fork that works with criterion 0.5
+criterion = { version = "0.5", default-features = false }
 
 [dev-dependencies.fail]
 version = "0.5.0"
@@ -109,7 +105,7 @@ mmap = ["fs4", "tempfile", "memmap2"]
 stopwords = []
 
 lz4-compression = ["lz4_flex"]
-zstd-compression = ["zstd"]
+zstd-compression = []
 
 failpoints = ["fail", "fail/failpoints"]
 unstable = [] # useful for benches.

benches/index-bench.rs

@@ -1,14 +1,99 @@
-use criterion::{criterion_group, criterion_main, Criterion, Throughput};
-use pprof::criterion::{Output, PProfProfiler};
+use criterion::{criterion_group, criterion_main, BatchSize, Bencher, Criterion, Throughput};
 use tantivy::schema::{TantivyDocument, FAST, INDEXED, STORED, STRING, TEXT};
-use tantivy::{Index, IndexWriter};
+use tantivy::{tokenizer, Index, IndexWriter};
 
 const HDFS_LOGS: &str = include_str!("hdfs.json");
 const GH_LOGS: &str = include_str!("gh.json");
 const WIKI: &str = include_str!("wiki.json");
 
-fn get_lines(input: &str) -> Vec<&str> {
-    input.trim().split('\n').collect()
+fn benchmark(
+    b: &mut Bencher,
+    input: &str,
+    schema: tantivy::schema::Schema,
+    commit: bool,
+    parse_json: bool,
+    is_dynamic: bool,
+) {
+    if is_dynamic {
+        benchmark_dynamic_json(b, input, schema, commit, parse_json)
+    } else {
+        _benchmark(b, input, schema, commit, parse_json, |schema, doc_json| {
+            TantivyDocument::parse_json(&schema, doc_json).unwrap()
+        })
+    }
+}
+
+fn get_index(schema: tantivy::schema::Schema) -> Index {
+    let mut index = Index::create_in_ram(schema.clone());
+    let ff_tokenizer_manager = tokenizer::TokenizerManager::default();
+    ff_tokenizer_manager.register(
+        "raw",
+        tokenizer::TextAnalyzer::builder(tokenizer::RawTokenizer::default())
+            .filter(tokenizer::RemoveLongFilter::limit(255))
+            .build(),
+    );
+    index.set_fast_field_tokenizers(ff_tokenizer_manager.clone());
+    index
+}
+
+fn _benchmark(
+    b: &mut Bencher,
+    input: &str,
+    schema: tantivy::schema::Schema,
+    commit: bool,
+    include_json_parsing: bool,
+    create_doc: impl Fn(&tantivy::schema::Schema, &str) -> TantivyDocument,
+) {
+    if include_json_parsing {
+        let lines: Vec<&str> = input.trim().split('\n').collect();
+        b.iter(|| {
+            let index = get_index(schema.clone());
+            let mut index_writer: IndexWriter =
+                index.writer_with_num_threads(1, 100_000_000).unwrap();
+            for doc_json in &lines {
+                let doc = create_doc(&schema, doc_json);
+                index_writer.add_document(doc).unwrap();
+            }
+            if commit {
+                index_writer.commit().unwrap();
+            }
+        })
+    } else {
+        let docs: Vec<_> = input
+            .trim()
+            .split('\n')
+            .map(|doc_json| create_doc(&schema, doc_json))
+            .collect();
+        b.iter_batched(
+            || docs.clone(),
+            |docs| {
+                let index = get_index(schema.clone());
+                let mut index_writer: IndexWriter =
+                    index.writer_with_num_threads(1, 100_000_000).unwrap();
+                for doc in docs {
+                    index_writer.add_document(doc).unwrap();
+                }
+                if commit {
+                    index_writer.commit().unwrap();
+                }
+            },
+            BatchSize::SmallInput,
+        )
+    }
+}
+fn benchmark_dynamic_json(
+    b: &mut Bencher,
+    input: &str,
+    schema: tantivy::schema::Schema,
+    commit: bool,
+    parse_json: bool,
+) {
+    let json_field = schema.get_field("json").unwrap();
+    _benchmark(b, input, schema, commit, parse_json, |_schema, doc_json| {
+        let json_val: serde_json::Map<String, serde_json::Value> =
+            serde_json::from_str(doc_json).unwrap();
+        tantivy::doc!(json_field=>json_val)
+    })
 }
 
 pub fn hdfs_index_benchmark(c: &mut Criterion) {
@@ -19,7 +104,14 @@ pub fn hdfs_index_benchmark(c: &mut Criterion) {
         schema_builder.add_text_field("severity", STRING);
         schema_builder.build()
     };
-    let schema_with_store = {
+    let schema_only_fast = {
+        let mut schema_builder = tantivy::schema::SchemaBuilder::new();
+        schema_builder.add_u64_field("timestamp", FAST);
+        schema_builder.add_text_field("body", FAST);
+        schema_builder.add_text_field("severity", FAST);
+        schema_builder.build()
+    };
+    let _schema_with_store = {
         let mut schema_builder = tantivy::schema::SchemaBuilder::new();
         schema_builder.add_u64_field("timestamp", INDEXED | STORED);
         schema_builder.add_text_field("body", TEXT | STORED);
@@ -28,77 +120,39 @@ pub fn hdfs_index_benchmark(c: &mut Criterion) {
     };
     let dynamic_schema = {
         let mut schema_builder = tantivy::schema::SchemaBuilder::new();
-        schema_builder.add_json_field("json", TEXT);
+        schema_builder.add_json_field("json", TEXT | FAST);
         schema_builder.build()
     };
 
     let mut group = c.benchmark_group("index-hdfs");
     group.throughput(Throughput::Bytes(HDFS_LOGS.len() as u64));
     group.sample_size(20);
-    group.bench_function("index-hdfs-no-commit", |b| {
-        let lines = get_lines(HDFS_LOGS);
-        b.iter(|| {
-            let index = Index::create_in_ram(schema.clone());
-            let index_writer: IndexWriter = index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for doc_json in &lines {
-                let doc = TantivyDocument::parse_json(&schema, doc_json).unwrap();
-                index_writer.add_document(doc).unwrap();
+
+    let benches = [
+        ("only-indexed-".to_string(), schema, false),
+        //("stored-".to_string(), _schema_with_store, false),
+        ("only-fast-".to_string(), schema_only_fast, false),
+        ("dynamic-".to_string(), dynamic_schema, true),
+    ];
+
+    for (prefix, schema, is_dynamic) in benches {
+        for commit in [false, true] {
+            let suffix = if commit { "with-commit" } else { "no-commit" };
+            for parse_json in [false] {
+                // for parse_json in [false, true] {
+                let suffix = if parse_json {
+                    format!("{}-with-json-parsing", suffix)
+                } else {
+                    format!("{}", suffix)
+                };
+
+                let bench_name = format!("{}{}", prefix, suffix);
+                group.bench_function(bench_name, |b| {
+                    benchmark(b, HDFS_LOGS, schema.clone(), commit, parse_json, is_dynamic)
+                });
             }
-        })
-    });
-    group.bench_function("index-hdfs-with-commit", |b| {
-        let lines = get_lines(HDFS_LOGS);
-        b.iter(|| {
-            let index = Index::create_in_ram(schema.clone());
-            let mut index_writer: IndexWriter =
-                index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for doc_json in &lines {
-                let doc = TantivyDocument::parse_json(&schema, doc_json).unwrap();
-                index_writer.add_document(doc).unwrap();
-            }
-            index_writer.commit().unwrap();
-        })
-    });
-    group.bench_function("index-hdfs-no-commit-with-docstore", |b| {
-        let lines = get_lines(HDFS_LOGS);
-        b.iter(|| {
-            let index = Index::create_in_ram(schema_with_store.clone());
-            let index_writer: IndexWriter = index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for doc_json in &lines {
-                let doc = TantivyDocument::parse_json(&schema, doc_json).unwrap();
-                index_writer.add_document(doc).unwrap();
-            }
-        })
-    });
-    group.bench_function("index-hdfs-with-commit-with-docstore", |b| {
-        let lines = get_lines(HDFS_LOGS);
-        b.iter(|| {
-            let index = Index::create_in_ram(schema_with_store.clone());
-            let mut index_writer: IndexWriter =
-                index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for doc_json in &lines {
-                let doc = TantivyDocument::parse_json(&schema, doc_json).unwrap();
-                index_writer.add_document(doc).unwrap();
-            }
-            index_writer.commit().unwrap();
-        })
-    });
-    group.bench_function("index-hdfs-no-commit-json-without-docstore", |b| {
-        let lines = get_lines(HDFS_LOGS);
-        b.iter(|| {
-            let index = Index::create_in_ram(dynamic_schema.clone());
-            let json_field = dynamic_schema.get_field("json").unwrap();
-            let mut index_writer: IndexWriter =
-                index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for doc_json in &lines {
-                let json_val: serde_json::Map<String, serde_json::Value> =
-                    serde_json::from_str(doc_json).unwrap();
-                let doc = tantivy::doc!(json_field=>json_val);
-                index_writer.add_document(doc).unwrap();
-            }
-            index_writer.commit().unwrap();
-        })
-    });
+        }
+    }
 }
 
 pub fn gh_index_benchmark(c: &mut Criterion) {
@@ -107,39 +161,24 @@ pub fn gh_index_benchmark(c: &mut Criterion) {
         schema_builder.add_json_field("json", TEXT | FAST);
         schema_builder.build()
     };
+    let dynamic_schema_fast = {
+        let mut schema_builder = tantivy::schema::SchemaBuilder::new();
+        schema_builder.add_json_field("json", FAST);
+        schema_builder.build()
+    };
 
     let mut group = c.benchmark_group("index-gh");
     group.throughput(Throughput::Bytes(GH_LOGS.len() as u64));
 
     group.bench_function("index-gh-no-commit", |b| {
-        let lines = get_lines(GH_LOGS);
-        b.iter(|| {
-            let json_field = dynamic_schema.get_field("json").unwrap();
-            let index = Index::create_in_ram(dynamic_schema.clone());
-            let index_writer: IndexWriter = index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for doc_json in &lines {
-                let json_val: serde_json::Map<String, serde_json::Value> =
-                    serde_json::from_str(doc_json).unwrap();
-                let doc = tantivy::doc!(json_field=>json_val);
-                index_writer.add_document(doc).unwrap();
-            }
-        })
+        benchmark_dynamic_json(b, GH_LOGS, dynamic_schema.clone(), false, false)
     });
-    group.bench_function("index-gh-with-commit", |b| {
-        let lines = get_lines(GH_LOGS);
-        b.iter(|| {
-            let json_field = dynamic_schema.get_field("json").unwrap();
-            let index = Index::create_in_ram(dynamic_schema.clone());
-            let mut index_writer: IndexWriter =
-                index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for doc_json in &lines {
-                let json_val: serde_json::Map<String, serde_json::Value> =
-                    serde_json::from_str(doc_json).unwrap();
-                let doc = tantivy::doc!(json_field=>json_val);
-                index_writer.add_document(doc).unwrap();
-            }
-            index_writer.commit().unwrap();
-        })
+    group.bench_function("index-gh-fast", |b| {
+        benchmark_dynamic_json(b, GH_LOGS, dynamic_schema_fast.clone(), false, false)
+    });
+
+    group.bench_function("index-gh-fast-with-commit", |b| {
+        benchmark_dynamic_json(b, GH_LOGS, dynamic_schema_fast.clone(), true, false)
     });
 }
 
@@ -154,34 +193,10 @@ pub fn wiki_index_benchmark(c: &mut Criterion) {
     group.throughput(Throughput::Bytes(WIKI.len() as u64));
 
     group.bench_function("index-wiki-no-commit", |b| {
-        let lines = get_lines(WIKI);
-        b.iter(|| {
-            let json_field = dynamic_schema.get_field("json").unwrap();
-            let index = Index::create_in_ram(dynamic_schema.clone());
-            let index_writer: IndexWriter = index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for doc_json in &lines {
-                let json_val: serde_json::Map<String, serde_json::Value> =
-                    serde_json::from_str(doc_json).unwrap();
-                let doc = tantivy::doc!(json_field=>json_val);
-                index_writer.add_document(doc).unwrap();
-            }
-        })
+        benchmark_dynamic_json(b, WIKI, dynamic_schema.clone(), false, false)
     });
     group.bench_function("index-wiki-with-commit", |b| {
-        let lines = get_lines(WIKI);
-        b.iter(|| {
-            let json_field = dynamic_schema.get_field("json").unwrap();
-            let index = Index::create_in_ram(dynamic_schema.clone());
-            let mut index_writer: IndexWriter =
-                index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for doc_json in &lines {
-                let json_val: serde_json::Map<String, serde_json::Value> =
-                    serde_json::from_str(doc_json).unwrap();
-                let doc = tantivy::doc!(json_field=>json_val);
-                index_writer.add_document(doc).unwrap();
-            }
-            index_writer.commit().unwrap();
-        })
+        benchmark_dynamic_json(b, WIKI, dynamic_schema.clone(), true, false)
     });
 }
 
@@ -192,12 +207,12 @@ criterion_group! {
 }
 criterion_group! {
     name = gh_benches;
-    config = Criterion::default().with_profiler(PProfProfiler::new(100, Output::Flamegraph(None)));
+    config = Criterion::default();
     targets = gh_index_benchmark
 }
 criterion_group! {
     name = wiki_benches;
-    config = Criterion::default().with_profiler(PProfProfiler::new(100, Output::Flamegraph(None)));
+    config = Criterion::default();
     targets = wiki_index_benchmark
 }
 criterion_main!(benches, gh_benches, wiki_benches);

bitpacker/Cargo.toml

@@ -15,7 +15,7 @@ homepage = "https://github.com/quickwit-oss/tantivy"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-bitpacking = {version="0.8", default-features=false, features = ["bitpacker1x"]}
+bitpacking = { version = "0.9.2", default-features = false, features = ["bitpacker1x"] }
 
 [dev-dependencies]
 rand = "0.8"

columnar/Cargo.toml

@@ -9,8 +9,7 @@ description = "column oriented storage for tantivy"
 categories = ["database-implementations", "data-structures", "compression"]
 
 [dependencies]
-itertools = "0.11.0"
-fnv = "1.0.7"
+itertools = "0.12.0"
 fastdivide = "0.4.0"
 
 stacker = { version= "0.2", path = "../stacker", package="tantivy-stacker"}

columnar/columnar-cli/Cargo.toml

@@ -8,7 +8,6 @@ license = "MIT"
 columnar = {path="../", package="tantivy-columnar"}
 serde_json = "1"
 serde_json_borrow = {git="https://github.com/PSeitz/serde_json_borrow/"}
-serde = "1"
 
 [workspace]
 members = []

columnar/src/columnar/column_type.rs

@@ -58,7 +58,7 @@ impl ColumnType {
         self == &ColumnType::DateTime
     }
 
-    pub(crate) fn try_from_code(code: u8) -> Result<ColumnType, InvalidData> {
+    pub fn try_from_code(code: u8) -> Result<ColumnType, InvalidData> {
         COLUMN_TYPES.get(code as usize).copied().ok_or(InvalidData)
     }
 }

columnar/src/columnar/writer/column_writers.rs

@@ -269,7 +269,8 @@ impl StrOrBytesColumnWriter {
         dictionaries: &mut [DictionaryBuilder],
         arena: &mut MemoryArena,
     ) {
-        let unordered_id = dictionaries[self.dictionary_id as usize].get_or_allocate_id(bytes);
+        let unordered_id =
+            dictionaries[self.dictionary_id as usize].get_or_allocate_id(bytes, arena);
         self.column_writer.record(doc, unordered_id, arena);
     }
 

columnar/src/columnar/writer/mod.rs

@@ -333,7 +333,7 @@ impl ColumnarWriter {
         num_docs: RowId,
         old_to_new_row_ids: Option<&[RowId]>,
         wrt: &mut dyn io::Write,
-    ) -> io::Result<()> {
+    ) -> io::Result<Vec<(String, ColumnType)>> {
         let mut serializer = ColumnarSerializer::new(wrt);
         let mut columns: Vec<(&[u8], ColumnType, Addr)> = self
             .numerical_field_hash_map
@@ -374,7 +374,9 @@ impl ColumnarWriter {
 
         let (arena, buffers, dictionaries) = (&self.arena, &mut self.buffers, &self.dictionaries);
         let mut symbol_byte_buffer: Vec<u8> = Vec::new();
-        for (column_name, column_type, addr) in columns {
+        for (column_name, column_type, addr) in columns.iter() {
+            let column_type = *column_type;
+            let addr = *addr;
             match column_type {
                 ColumnType::Bool => {
                     let column_writer: ColumnWriter = self.bool_field_hash_map.read(addr);
@@ -437,6 +439,7 @@ impl ColumnarWriter {
                             &mut symbol_byte_buffer,
                         ),
                         buffers,
+                        &self.arena,
                         &mut column_serializer,
                     )?;
                     column_serializer.finalize()?;
@@ -484,12 +487,21 @@ impl ColumnarWriter {
             };
         }
         serializer.finalize(num_docs)?;
-        Ok(())
+        Ok(columns
+            .into_iter()
+            .map(|(column_name, column_type, _)| {
+                (
+                    String::from_utf8_lossy(column_name).to_string(),
+                    column_type,
+                )
+            })
+            .collect())
     }
 }
 
 // Serialize [Dictionary, Column, dictionary num bytes U32::LE]
 // Column: [Column Index, Column Values, column index num bytes U32::LE]
+#[allow(clippy::too_many_arguments)]
 fn serialize_bytes_or_str_column(
     cardinality: Cardinality,
     num_docs: RowId,
@@ -497,6 +509,7 @@ fn serialize_bytes_or_str_column(
     dictionary_builder: &DictionaryBuilder,
     operation_it: impl Iterator<Item = ColumnOperation<UnorderedId>>,
     buffers: &mut SpareBuffers,
+    arena: &MemoryArena,
     wrt: impl io::Write,
 ) -> io::Result<()> {
     let SpareBuffers {
@@ -505,7 +518,8 @@ fn serialize_bytes_or_str_column(
         ..
     } = buffers;
     let mut counting_writer = CountingWriter::wrap(wrt);
-    let term_id_mapping: TermIdMapping = dictionary_builder.serialize(&mut counting_writer)?;
+    let term_id_mapping: TermIdMapping =
+        dictionary_builder.serialize(arena, &mut counting_writer)?;
     let dictionary_num_bytes: u32 = counting_writer.written_bytes() as u32;
     let mut wrt = counting_writer.finish();
     let operation_iterator = operation_it.map(|symbol: ColumnOperation<UnorderedId>| {

columnar/src/dictionary.rs

@@ -1,7 +1,7 @@
 use std::io;
 
-use fnv::FnvHashMap;
 use sstable::SSTable;
+use stacker::{MemoryArena, SharedArenaHashMap};
 
 pub(crate) struct TermIdMapping {
     unordered_to_ord: Vec<OrderedId>,
@@ -31,29 +31,38 @@ pub struct OrderedId(pub u32);
 /// mapping.
 #[derive(Default)]
 pub(crate) struct DictionaryBuilder {
-    dict: FnvHashMap<Vec<u8>, UnorderedId>,
-    memory_consumption: usize,
+    dict: SharedArenaHashMap,
 }
 
 impl DictionaryBuilder {
     /// Get or allocate an unordered id.
     /// (This ID is simply an auto-incremented id.)
-    pub fn get_or_allocate_id(&mut self, term: &[u8]) -> UnorderedId {
-        if let Some(term_id) = self.dict.get(term) {
-            return *term_id;
-        }
-        let new_id = UnorderedId(self.dict.len() as u32);
-        self.dict.insert(term.to_vec(), new_id);
-        self.memory_consumption += term.len();
-        self.memory_consumption += 40; // Term Metadata + HashMap overhead
-        new_id
+    pub fn get_or_allocate_id(&mut self, term: &[u8], arena: &mut MemoryArena) -> UnorderedId {
+        let next_id = self.dict.len() as u32;
+        let unordered_id = self
+            .dict
+            .mutate_or_create(term, arena, |unordered_id: Option<u32>| {
+                if let Some(unordered_id) = unordered_id {
+                    unordered_id
+                } else {
+                    next_id
+                }
+            });
+        UnorderedId(unordered_id)
     }
 
     /// Serialize the dictionary into an fst, and returns the
     /// `UnorderedId -> TermOrdinal` map.
-    pub fn serialize<'a, W: io::Write + 'a>(&self, wrt: &mut W) -> io::Result<TermIdMapping> {
-        let mut terms: Vec<(&[u8], UnorderedId)> =
-            self.dict.iter().map(|(k, v)| (k.as_slice(), *v)).collect();
+    pub fn serialize<'a, W: io::Write + 'a>(
+        &self,
+        arena: &MemoryArena,
+        wrt: &mut W,
+    ) -> io::Result<TermIdMapping> {
+        let mut terms: Vec<(&[u8], UnorderedId)> = self
+            .dict
+            .iter(arena)
+            .map(|(k, v)| (k, arena.read(v)))
+            .collect();
         terms.sort_unstable_by_key(|(key, _)| *key);
         // TODO Remove the allocation.
         let mut unordered_to_ord: Vec<OrderedId> = vec![OrderedId(0u32); terms.len()];
@@ -68,7 +77,7 @@ impl DictionaryBuilder {
     }
 
     pub(crate) fn mem_usage(&self) -> usize {
-        self.memory_consumption
+        self.dict.mem_usage()
     }
 }
 
@@ -78,12 +87,13 @@ mod tests {
 
     #[test]
     fn test_dictionary_builder() {
+        let mut arena = MemoryArena::default();
         let mut dictionary_builder = DictionaryBuilder::default();
-        let hello_uid = dictionary_builder.get_or_allocate_id(b"hello");
-        let happy_uid = dictionary_builder.get_or_allocate_id(b"happy");
-        let tax_uid = dictionary_builder.get_or_allocate_id(b"tax");
+        let hello_uid = dictionary_builder.get_or_allocate_id(b"hello", &mut arena);
+        let happy_uid = dictionary_builder.get_or_allocate_id(b"happy", &mut arena);
+        let tax_uid = dictionary_builder.get_or_allocate_id(b"tax", &mut arena);
         let mut buffer = Vec::new();
-        let id_mapping = dictionary_builder.serialize(&mut buffer).unwrap();
+        let id_mapping = dictionary_builder.serialize(&arena, &mut buffer).unwrap();
         assert_eq!(id_mapping.to_ord(hello_uid), OrderedId(1));
         assert_eq!(id_mapping.to_ord(happy_uid), OrderedId(0));
         assert_eq!(id_mapping.to_ord(tax_uid), OrderedId(2));

columnar/src/lib.rs

@@ -1,3 +1,22 @@
+//! # Tantivy-Columnar
+//!
+//! `tantivy-columnar`provides a columnar storage for tantivy.
+//! The crate allows for efficient read operations on specific columns rather than entire records.
+//!
+//! ## Overview
+//!
+//! - **columnar**: Reading, writing, and merging multiple columns:
+//!   - **[ColumnarWriter]**: Makes it possible to create a new columnar.
+//!   - **[ColumnarReader]**: The ColumnarReader makes it possible to access a set of columns
+//!     associated to field names.
+//!   - **[merge_columnar]**: Contains the functionalities to merge multiple ColumnarReader or
+//!     segments into a single one.
+//!
+//! - **column**: A single column, which contains
+//!     - [column_index]: Resolves the rows for a document id. Manages the cardinality of the
+//!       column.
+//!     - [column_values]: Stores the values of a column in a dense format.
+
 #![cfg_attr(all(feature = "unstable", test), feature(test))]
 
 #[cfg(test)]

columnar/src/tests.rs

@@ -26,7 +26,7 @@ fn test_dataframe_writer_str() {
     assert_eq!(columnar.num_columns(), 1);
     let cols: Vec<DynamicColumnHandle> = columnar.read_columns("my_string").unwrap();
     assert_eq!(cols.len(), 1);
-    assert_eq!(cols[0].num_bytes(), 99);
+    assert_eq!(cols[0].num_bytes(), 73);
 }
 
 #[test]
@@ -40,7 +40,7 @@ fn test_dataframe_writer_bytes() {
     assert_eq!(columnar.num_columns(), 1);
     let cols: Vec<DynamicColumnHandle> = columnar.read_columns("my_string").unwrap();
     assert_eq!(cols.len(), 1);
-    assert_eq!(cols[0].num_bytes(), 99);
+    assert_eq!(cols[0].num_bytes(), 73);
 }
 
 #[test]

common/src/bitset.rs

@@ -6,7 +6,7 @@ use ownedbytes::OwnedBytes;
 
 use crate::ByteCount;
 
-#[derive(Clone, Copy, Eq, PartialEq)]
+#[derive(Clone, Copy, Eq, PartialEq, Hash)]
 pub struct TinySet(u64);
 
 impl fmt::Debug for TinySet {

ownedbytes/src/lib.rs

@@ -1,5 +1,5 @@
 use std::convert::TryInto;
-use std::ops::Deref;
+use std::ops::{Deref, Range};
 use std::sync::Arc;
 use std::{fmt, io};
 
@@ -37,7 +37,7 @@ impl OwnedBytes {
     /// creates a fileslice that is just a view over a slice of the data.
     #[must_use]
     #[inline]
-    pub fn slice(&self, range: impl std::slice::SliceIndex<[u8], Output = [u8]>) -> Self {
+    pub fn slice(&self, range: Range<usize>) -> Self {
         OwnedBytes {
             data: &self.data[range],
             box_stable_deref: self.box_stable_deref.clone(),

src/aggregation/agg_tests.rs

@@ -624,6 +624,65 @@ fn test_aggregation_on_json_object() {
     );
 }
 
+#[test]
+fn test_aggregation_on_nested_json_object() {
+    let mut schema_builder = Schema::builder();
+    let json = schema_builder.add_json_field("json.blub", FAST);
+    let schema = schema_builder.build();
+    let index = Index::create_in_ram(schema);
+    let mut index_writer: IndexWriter = index.writer_for_tests().unwrap();
+    index_writer
+        .add_document(doc!(json => json!({"color.dot": "red", "color": {"nested":"red"} })))
+        .unwrap();
+    index_writer
+        .add_document(doc!(json => json!({"color.dot": "blue", "color": {"nested":"blue"} })))
+        .unwrap();
+    index_writer.commit().unwrap();
+    let reader = index.reader().unwrap();
+    let searcher = reader.searcher();
+
+    let agg: Aggregations = serde_json::from_value(json!({
+        "jsonagg1": {
+            "terms": {
+                "field": "json\\.blub.color\\.dot",
+            }
+        },
+        "jsonagg2": {
+            "terms": {
+                "field": "json\\.blub.color.nested",
+            }
+        }
+
+    }))
+    .unwrap();
+
+    let aggregation_collector = get_collector(agg);
+    let aggregation_results = searcher.search(&AllQuery, &aggregation_collector).unwrap();
+    let aggregation_res_json = serde_json::to_value(aggregation_results).unwrap();
+    assert_eq!(
+        &aggregation_res_json,
+        &serde_json::json!({
+            "jsonagg1": {
+                "buckets": [
+                    {"doc_count": 1, "key": "blue"},
+                    {"doc_count": 1, "key": "red"}
+                ],
+                "doc_count_error_upper_bound": 0,
+                "sum_other_doc_count": 0
+            },
+            "jsonagg2": {
+                "buckets": [
+                    {"doc_count": 1, "key": "blue"},
+                    {"doc_count": 1, "key": "red"}
+                ],
+                "doc_count_error_upper_bound": 0,
+                "sum_other_doc_count": 0
+            }
+
+        })
+    );
+}
+
 #[test]
 fn test_aggregation_on_json_object_empty_columns() {
     let mut schema_builder = Schema::builder();

src/core/index.rs

@@ -23,6 +23,7 @@ use crate::reader::{IndexReader, IndexReaderBuilder};
 use crate::schema::document::Document;
 use crate::schema::{Field, FieldType, Schema};
 use crate::tokenizer::{TextAnalyzer, TokenizerManager};
+use crate::{merge_field_meta_data, FieldMetadata, SegmentReader};
 
 fn load_metas(
     directory: &dyn Directory,
@@ -489,6 +490,28 @@ impl Index {
         self.inventory.all()
     }
 
+    /// Returns the list of fields that have been indexed in the Index.
+    /// The field list includes the field defined in the schema as well as the fields
+    /// that have been indexed as a part of a JSON field.
+    /// The returned field name is the full field name, including the name of the JSON field.
+    ///
+    /// The returned field names can be used in queries.
+    ///
+    /// Notice: If your data contains JSON fields this is **very expensive**, as it requires
+    /// browsing through the inverted index term dictionary and the columnar field dictionary.
+    ///
+    /// Disclaimer: Some fields may not be listed here. For instance, if the schema contains a json
+    /// field that is not indexed nor a fast field but is stored, it is possible for the field
+    /// to not be listed.
+    pub fn fields_metadata(&self) -> crate::Result<Vec<FieldMetadata>> {
+        let segments = self.searchable_segments()?;
+        let fields_metadata: Vec<Vec<FieldMetadata>> = segments
+            .into_iter()
+            .map(|segment| SegmentReader::open(&segment)?.fields_metadata())
+            .collect::<Result<_, _>>()?;
+        Ok(merge_field_meta_data(fields_metadata, &self.schema()))
+    }
+
     /// Creates a new segment_meta (Advanced user only).
     ///
     /// As long as the `SegmentMeta` lives, the files associated with the

src/core/index_meta.rs

@@ -142,6 +142,7 @@ impl SegmentMeta {
             SegmentComponent::FastFields => ".fast".to_string(),
             SegmentComponent::FieldNorms => ".fieldnorm".to_string(),
             SegmentComponent::Delete => format!(".{}.del", self.delete_opstamp().unwrap_or(0)),
+            SegmentComponent::FieldList => ".fieldlist".to_string(),
         });
         PathBuf::from(path)
     }

src/core/inverted_index_reader.rs

@@ -70,12 +70,12 @@ impl InvertedIndexReader {
         &self.termdict
     }
 
-    /// Return the fields and types encoded in the dictionary in lexicographic oder.
+    /// Return the fields and types encoded in the dictionary in lexicographic order.
     /// Only valid on JSON fields.
     ///
     /// Notice: This requires a full scan and therefore **very expensive**.
     /// TODO: Move to sstable to use the index.
-    pub fn list_fields(&self) -> io::Result<Vec<(String, Type)>> {
+    pub fn list_encoded_fields(&self) -> io::Result<Vec<(String, Type)>> {
         let mut stream = self.termdict.stream()?;
         let mut fields = Vec::new();
         let mut fields_set = FnvHashSet::default();

src/core/json_utils.rs

@@ -1,4 +1,4 @@
-use columnar::MonotonicallyMappableToU64;
+use columnar::{ColumnType, MonotonicallyMappableToU64};
 use common::{replace_in_place, JsonPathWriter};
 use rustc_hash::FxHashMap;
 
@@ -62,6 +62,14 @@ impl IndexingPositionsPerPath {
     }
 }
 
+/// Convert JSON_PATH_SEGMENT_SEP to a dot.
+pub fn json_path_sep_to_dot(path: &mut str) {
+    // This is safe since we are replacing a ASCII character by another ASCII character.
+    unsafe {
+        replace_in_place(JSON_PATH_SEGMENT_SEP, b'.', path.as_bytes_mut());
+    }
+}
+
 #[allow(clippy::too_many_arguments)]
 pub(crate) fn index_json_values<'a, V: Value<'a>>(
     doc: DocId,
@@ -145,7 +153,7 @@ fn index_json_value<'a, V: Value<'a>>(
                 let mut token_stream = text_analyzer.token_stream(val);
                 let unordered_id = ctx
                     .path_to_unordered_id
-                    .get_or_allocate_unordered_id(json_path_writer.as_str());
+                    .get_or_allocate_unordered_id(json_path_writer.as_str(), ColumnType::Str);
 
                 // TODO: make sure the chain position works out.
                 set_path_id(term_buffer, unordered_id);
@@ -163,7 +171,7 @@ fn index_json_value<'a, V: Value<'a>>(
                 set_path_id(
                     term_buffer,
                     ctx.path_to_unordered_id
-                        .get_or_allocate_unordered_id(json_path_writer.as_str()),
+                        .get_or_allocate_unordered_id(json_path_writer.as_str(), ColumnType::U64),
                 );
                 term_buffer.append_type_and_fast_value(val);
                 postings_writer.subscribe(doc, 0u32, term_buffer, ctx);
@@ -172,7 +180,7 @@ fn index_json_value<'a, V: Value<'a>>(
                 set_path_id(
                     term_buffer,
                     ctx.path_to_unordered_id
-                        .get_or_allocate_unordered_id(json_path_writer.as_str()),
+                        .get_or_allocate_unordered_id(json_path_writer.as_str(), ColumnType::I64),
                 );
                 term_buffer.append_type_and_fast_value(val);
                 postings_writer.subscribe(doc, 0u32, term_buffer, ctx);
@@ -181,7 +189,7 @@ fn index_json_value<'a, V: Value<'a>>(
                 set_path_id(
                     term_buffer,
                     ctx.path_to_unordered_id
-                        .get_or_allocate_unordered_id(json_path_writer.as_str()),
+                        .get_or_allocate_unordered_id(json_path_writer.as_str(), ColumnType::F64),
                 );
                 term_buffer.append_type_and_fast_value(val);
                 postings_writer.subscribe(doc, 0u32, term_buffer, ctx);
@@ -190,7 +198,7 @@ fn index_json_value<'a, V: Value<'a>>(
                 set_path_id(
                     term_buffer,
                     ctx.path_to_unordered_id
-                        .get_or_allocate_unordered_id(json_path_writer.as_str()),
+                        .get_or_allocate_unordered_id(json_path_writer.as_str(), ColumnType::Bool),
                 );
                 term_buffer.append_type_and_fast_value(val);
                 postings_writer.subscribe(doc, 0u32, term_buffer, ctx);
@@ -198,8 +206,10 @@ fn index_json_value<'a, V: Value<'a>>(
             ReferenceValueLeaf::Date(val) => {
                 set_path_id(
                     term_buffer,
-                    ctx.path_to_unordered_id
-                        .get_or_allocate_unordered_id(json_path_writer.as_str()),
+                    ctx.path_to_unordered_id.get_or_allocate_unordered_id(
+                        json_path_writer.as_str(),
+                        ColumnType::DateTime,
+                    ),
                 );
                 term_buffer.append_type_and_fast_value(val);
                 postings_writer.subscribe(doc, 0u32, term_buffer, ctx);
@@ -320,7 +330,7 @@ pub struct JsonTermWriter<'a> {
 /// In other words,
 /// - `k8s.node` ends up as `["k8s", "node"]`.
 /// - `k8s\.node` ends up as `["k8s.node"]`.
-fn split_json_path(json_path: &str) -> Vec<String> {
+pub fn split_json_path(json_path: &str) -> Vec<String> {
     let mut escaped_state: bool = false;
     let mut json_path_segments = Vec::new();
     let mut buffer = String::new();

src/core/mod.rs

@@ -25,7 +25,7 @@ pub use self::searcher::{Searcher, SearcherGeneration};
 pub use self::segment::Segment;
 pub use self::segment_component::SegmentComponent;
 pub use self::segment_id::SegmentId;
-pub use self::segment_reader::SegmentReader;
+pub use self::segment_reader::{merge_field_meta_data, FieldMetadata, SegmentReader};
 pub use self::single_segment_index_writer::SingleSegmentIndexWriter;
 
 /// The meta file contains all the information about the list of segments and the schema

src/core/segment_component.rs

@@ -27,12 +27,14 @@ pub enum SegmentComponent {
     /// Bitset describing which document of the segment is alive.
     /// (It was representing deleted docs but changed to represent alive docs from v0.17)
     Delete,
+    /// Field list describing the fields in the segment.
+    FieldList,
 }
 
 impl SegmentComponent {
     /// Iterates through the components.
     pub fn iterator() -> slice::Iter<'static, SegmentComponent> {
-        static SEGMENT_COMPONENTS: [SegmentComponent; 8] = [
+        static SEGMENT_COMPONENTS: [SegmentComponent; 9] = [
             SegmentComponent::Postings,
             SegmentComponent::Positions,
             SegmentComponent::FastFields,
@@ -41,6 +43,7 @@ impl SegmentComponent {
             SegmentComponent::Store,
             SegmentComponent::TempStore,
             SegmentComponent::Delete,
+            SegmentComponent::FieldList,
         ];
         SEGMENT_COMPONENTS.iter()
     }

src/core/segment_reader.rs

@@ -1,11 +1,15 @@
 use std::collections::HashMap;
+use std::ops::BitOrAssign;
 use std::sync::{Arc, RwLock};
 use std::{fmt, io};
 
+use itertools::Itertools;
+
 use crate::core::{InvertedIndexReader, Segment, SegmentComponent, SegmentId};
 use crate::directory::{CompositeFile, FileSlice};
 use crate::error::DataCorruption;
 use crate::fastfield::{intersect_alive_bitsets, AliveBitSet, FacetReader, FastFieldReaders};
+use crate::field_list::read_split_fields;
 use crate::fieldnorm::{FieldNormReader, FieldNormReaders};
 use crate::schema::{Field, IndexRecordOption, Schema, Type};
 use crate::space_usage::SegmentSpaceUsage;
@@ -39,6 +43,7 @@ pub struct SegmentReader {
     fast_fields_readers: FastFieldReaders,
     fieldnorm_readers: FieldNormReaders,
 
+    list_fields_file: Option<FileSlice>, // Optional field list file for backwards compatibility
     store_file: FileSlice,
     alive_bitset_opt: Option<AliveBitSet>,
     schema: Schema,
@@ -148,6 +153,7 @@ impl SegmentReader {
         let termdict_composite = CompositeFile::open(&termdict_file)?;
 
         let store_file = segment.open_read(SegmentComponent::Store)?;
+        let list_fields_file = segment.open_read(SegmentComponent::FieldList).ok();
 
         crate::fail_point!("SegmentReader::open#middle");
 
@@ -196,6 +202,7 @@ impl SegmentReader {
             segment_id: segment.id(),
             delete_opstamp: segment.meta().delete_opstamp(),
             store_file,
+            list_fields_file,
             alive_bitset_opt,
             positions_composite,
             schema,
@@ -280,6 +287,41 @@ impl SegmentReader {
         Ok(inv_idx_reader)
     }
 
+    /// Returns the list of fields that have been indexed in the segment.
+    /// The field list includes the field defined in the schema as well as the fields
+    /// that have been indexed as a part of a JSON field.
+    /// The returned field name is the full field name, including the name of the JSON field.
+    ///
+    /// The returned field names can be used in queries.
+    ///
+    /// Notice: If your data contains JSON fields this is **very expensive**, as it requires
+    /// browsing through the inverted index term dictionary and the columnar field dictionary.
+    ///
+    /// Disclaimer: Some fields may not be listed here. For instance, if the schema contains a json
+    /// field that is not indexed nor a fast field but is stored, it is possible for the field
+    /// to not be listed.
+    pub fn fields_metadata(&self) -> crate::Result<Vec<FieldMetadata>> {
+        if let Some(list_fields_file) = self.list_fields_file.as_ref() {
+            let file = list_fields_file.read_bytes()?;
+            let fields_metadata =
+                read_split_fields(file)?.collect::<io::Result<Vec<FieldMetadata>>>();
+            fields_metadata.map_err(|e| e.into())
+        } else {
+            // Schema fallback
+            Ok(self
+                .schema()
+                .fields()
+                .map(|(_field, entry)| FieldMetadata {
+                    field_name: entry.name().to_string(),
+                    typ: entry.field_type().value_type(),
+                    indexed: entry.is_indexed(),
+                    stored: entry.is_stored(),
+                    fast: entry.is_fast(),
+                })
+                .collect())
+        }
+    }
+
     /// Returns the segment id
     pub fn segment_id(&self) -> SegmentId {
         self.segment_id
@@ -330,6 +372,65 @@ impl SegmentReader {
     }
 }
 
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+/// FieldMetadata
+pub struct FieldMetadata {
+    /// The field name
+    // Notice: Don't reorder the declaration of 1.field_name 2.typ, as it is used for ordering by
+    // field_name then typ.
+    pub field_name: String,
+    /// The field type
+    // Notice: Don't reorder the declaration of 1.field_name 2.typ, as it is used for ordering by
+    // field_name then typ.
+    pub typ: Type,
+    /// Is the field indexed for search
+    pub indexed: bool,
+    /// Is the field stored in the doc store
+    pub stored: bool,
+    /// Is the field stored in the columnar storage
+    pub fast: bool,
+}
+impl BitOrAssign for FieldMetadata {
+    fn bitor_assign(&mut self, rhs: Self) {
+        assert!(self.field_name == rhs.field_name);
+        assert!(self.typ == rhs.typ);
+        self.indexed |= rhs.indexed;
+        self.stored |= rhs.stored;
+        self.fast |= rhs.fast;
+    }
+}
+
+// Maybe too slow for the high cardinality case
+fn is_field_stored(field_name: &str, schema: &Schema) -> bool {
+    schema
+        .find_field(field_name)
+        .map(|(field, _path)| schema.get_field_entry(field).is_stored())
+        .unwrap_or(false)
+}
+
+/// Helper to merge the field metadata from multiple segments.
+pub fn merge_field_meta_data(
+    field_metadatas: Vec<Vec<FieldMetadata>>,
+    schema: &Schema,
+) -> Vec<FieldMetadata> {
+    let mut merged_field_metadata = Vec::new();
+    for (_key, mut group) in &field_metadatas
+        .into_iter()
+        .kmerge_by(|left, right| left < right)
+        // TODO: Remove allocation
+        .group_by(|el| (el.field_name.to_string(), el.typ))
+    {
+        let mut merged: FieldMetadata = group.next().unwrap();
+        for el in group {
+            merged |= el;
+        }
+        // Currently is_field_stored is maybe too slow for the high cardinality case
+        merged.stored = is_field_stored(&merged.field_name, schema);
+        merged_field_metadata.push(merged);
+    }
+    merged_field_metadata
+}
+
 fn intersect_alive_bitset(
     left_opt: Option<AliveBitSet>,
     right_opt: Option<AliveBitSet>,
@@ -353,9 +454,127 @@ impl fmt::Debug for SegmentReader {
 
 #[cfg(test)]
 mod test {
+    use super::*;
     use crate::core::Index;
-    use crate::schema::{Schema, Term, STORED, TEXT};
-    use crate::{DocId, IndexWriter};
+    use crate::schema::{Schema, SchemaBuilder, Term, STORED, TEXT};
+    use crate::{DocId, FieldMetadata, IndexWriter};
+
+    #[test]
+    fn test_merge_field_meta_data_same() {
+        let schema = SchemaBuilder::new().build();
+        let field_metadata1 = FieldMetadata {
+            field_name: "a".to_string(),
+            typ: crate::schema::Type::Str,
+            indexed: true,
+            stored: false,
+            fast: true,
+        };
+        let field_metadata2 = FieldMetadata {
+            field_name: "a".to_string(),
+            typ: crate::schema::Type::Str,
+            indexed: true,
+            stored: false,
+            fast: true,
+        };
+        let res = merge_field_meta_data(
+            vec![vec![field_metadata1.clone()], vec![field_metadata2]],
+            &schema,
+        );
+        assert_eq!(res, vec![field_metadata1]);
+    }
+    #[test]
+    fn test_merge_field_meta_data_different() {
+        let schema = SchemaBuilder::new().build();
+        let field_metadata1 = FieldMetadata {
+            field_name: "a".to_string(),
+            typ: crate::schema::Type::Str,
+            indexed: false,
+            stored: false,
+            fast: true,
+        };
+        let field_metadata2 = FieldMetadata {
+            field_name: "b".to_string(),
+            typ: crate::schema::Type::Str,
+            indexed: false,
+            stored: false,
+            fast: true,
+        };
+        let field_metadata3 = FieldMetadata {
+            field_name: "a".to_string(),
+            typ: crate::schema::Type::Str,
+            indexed: true,
+            stored: false,
+            fast: false,
+        };
+        let res = merge_field_meta_data(
+            vec![
+                vec![field_metadata1.clone(), field_metadata2.clone()],
+                vec![field_metadata3],
+            ],
+            &schema,
+        );
+        let field_metadata_expected1 = FieldMetadata {
+            field_name: "a".to_string(),
+            typ: crate::schema::Type::Str,
+            indexed: true,
+            stored: false,
+            fast: true,
+        };
+        assert_eq!(res, vec![field_metadata_expected1, field_metadata2.clone()]);
+    }
+    #[test]
+    fn test_merge_field_meta_data_merge() {
+        use pretty_assertions::assert_eq;
+        let get_meta_data = |name: &str, typ: Type| FieldMetadata {
+            field_name: name.to_string(),
+            typ,
+            indexed: false,
+            stored: false,
+            fast: true,
+        };
+        let schema = SchemaBuilder::new().build();
+        let mut metas = vec![get_meta_data("d", Type::Str), get_meta_data("e", Type::U64)];
+        metas.sort();
+        let res = merge_field_meta_data(vec![vec![get_meta_data("e", Type::Str)], metas], &schema);
+        assert_eq!(
+            res,
+            vec![
+                get_meta_data("d", Type::Str),
+                get_meta_data("e", Type::Str),
+                get_meta_data("e", Type::U64),
+            ]
+        );
+    }
+    #[test]
+    fn test_merge_field_meta_data_bitxor() {
+        let field_metadata1 = FieldMetadata {
+            field_name: "a".to_string(),
+            typ: crate::schema::Type::Str,
+            indexed: false,
+            stored: false,
+            fast: true,
+        };
+        let field_metadata2 = FieldMetadata {
+            field_name: "a".to_string(),
+            typ: crate::schema::Type::Str,
+            indexed: true,
+            stored: false,
+            fast: false,
+        };
+        let field_metadata_expected = FieldMetadata {
+            field_name: "a".to_string(),
+            typ: crate::schema::Type::Str,
+            indexed: true,
+            stored: false,
+            fast: true,
+        };
+        let mut res1 = field_metadata1.clone();
+        res1 |= field_metadata2.clone();
+        let mut res2 = field_metadata2.clone();
+        res2 |= field_metadata1;
+        assert_eq!(res1, field_metadata_expected);
+        assert_eq!(res2, field_metadata_expected);
+    }
 
     #[test]
     fn test_num_alive() -> crate::Result<()> {

src/core/tests.rs

@@ -1,12 +1,13 @@
 use crate::collector::Count;
 use crate::directory::{RamDirectory, WatchCallback};
-use crate::indexer::NoMergePolicy;
+use crate::indexer::{LogMergePolicy, NoMergePolicy};
+use crate::json_utils::JsonTermWriter;
 use crate::query::TermQuery;
-use crate::schema::{Field, IndexRecordOption, Schema, INDEXED, STRING, TEXT};
+use crate::schema::{Field, IndexRecordOption, Schema, Type, INDEXED, STRING, TEXT};
 use crate::tokenizer::TokenizerManager;
 use crate::{
-    Directory, Index, IndexBuilder, IndexReader, IndexSettings, IndexWriter, ReloadPolicy,
-    SegmentId, TantivyDocument, Term,
+    Directory, DocSet, Index, IndexBuilder, IndexReader, IndexSettings, IndexWriter, Postings,
+    ReloadPolicy, SegmentId, TantivyDocument, Term,
 };
 
 #[test]
@@ -344,3 +345,132 @@ fn test_merging_segment_update_docfreq() {
     let term_info = inv_index.get_term_info(&term).unwrap().unwrap();
     assert_eq!(term_info.doc_freq, 12);
 }
+
+// motivated by https://github.com/quickwit-oss/quickwit/issues/4130
+#[test]
+fn test_positions_merge_bug_non_text_json_vint() {
+    let mut schema_builder = Schema::builder();
+    let field = schema_builder.add_json_field("dynamic", TEXT);
+    let schema = schema_builder.build();
+    let index = Index::create_in_ram(schema.clone());
+    let mut writer: IndexWriter = index.writer_for_tests().unwrap();
+    let mut merge_policy = LogMergePolicy::default();
+    merge_policy.set_min_num_segments(2);
+    writer.set_merge_policy(Box::new(merge_policy));
+    // Here a string would work.
+    let doc_json = r#"{"tenant_id":75}"#;
+    let vals = serde_json::from_str(doc_json).unwrap();
+    let mut doc = TantivyDocument::default();
+    doc.add_object(field, vals);
+    writer.add_document(doc.clone()).unwrap();
+    writer.commit().unwrap();
+    writer.add_document(doc.clone()).unwrap();
+    writer.commit().unwrap();
+    writer.wait_merging_threads().unwrap();
+    let reader = index.reader().unwrap();
+    assert_eq!(reader.searcher().segment_readers().len(), 1);
+}
+
+// Same as above but with bitpacked blocks
+#[test]
+fn test_positions_merge_bug_non_text_json_bitpacked_block() {
+    let mut schema_builder = Schema::builder();
+    let field = schema_builder.add_json_field("dynamic", TEXT);
+    let schema = schema_builder.build();
+    let index = Index::create_in_ram(schema.clone());
+    let mut writer: IndexWriter = index.writer_for_tests().unwrap();
+    let mut merge_policy = LogMergePolicy::default();
+    merge_policy.set_min_num_segments(2);
+    writer.set_merge_policy(Box::new(merge_policy));
+    // Here a string would work.
+    let doc_json = r#"{"tenant_id":75}"#;
+    let vals = serde_json::from_str(doc_json).unwrap();
+    let mut doc = TantivyDocument::default();
+    doc.add_object(field, vals);
+    for _ in 0..128 {
+        writer.add_document(doc.clone()).unwrap();
+    }
+    writer.commit().unwrap();
+    writer.add_document(doc.clone()).unwrap();
+    writer.commit().unwrap();
+    writer.wait_merging_threads().unwrap();
+    let reader = index.reader().unwrap();
+    assert_eq!(reader.searcher().segment_readers().len(), 1);
+}
+
+#[test]
+fn test_non_text_json_term_freq() {
+    let mut schema_builder = Schema::builder();
+    let field = schema_builder.add_json_field("dynamic", TEXT);
+    let schema = schema_builder.build();
+    let index = Index::create_in_ram(schema.clone());
+    let mut writer: IndexWriter = index.writer_for_tests().unwrap();
+    // Here a string would work.
+    let doc_json = r#"{"tenant_id":75}"#;
+    let vals = serde_json::from_str(doc_json).unwrap();
+    let mut doc = TantivyDocument::default();
+    doc.add_object(field, vals);
+    writer.add_document(doc.clone()).unwrap();
+    writer.commit().unwrap();
+    let reader = index.reader().unwrap();
+    assert_eq!(reader.searcher().segment_readers().len(), 1);
+    let searcher = reader.searcher();
+    let segment_reader = searcher.segment_reader(0u32);
+    let inv_idx = segment_reader.inverted_index(field).unwrap();
+    let mut term = Term::with_type_and_field(Type::Json, field);
+    let mut json_term_writer = JsonTermWriter::wrap(&mut term, false);
+    json_term_writer.push_path_segment("tenant_id");
+    json_term_writer.close_path_and_set_type(Type::U64);
+    json_term_writer.set_fast_value(75u64);
+    let postings = inv_idx
+        .read_postings(
+            &json_term_writer.term(),
+            IndexRecordOption::WithFreqsAndPositions,
+        )
+        .unwrap()
+        .unwrap();
+    assert_eq!(postings.doc(), 0);
+    assert_eq!(postings.term_freq(), 1u32);
+}
+
+#[test]
+fn test_non_text_json_term_freq_bitpacked() {
+    let mut schema_builder = Schema::builder();
+    let field = schema_builder.add_json_field("dynamic", TEXT);
+    let schema = schema_builder.build();
+    let index = Index::create_in_ram(schema.clone());
+    let mut writer: IndexWriter = index.writer_for_tests().unwrap();
+    // Here a string would work.
+    let doc_json = r#"{"tenant_id":75}"#;
+    let vals = serde_json::from_str(doc_json).unwrap();
+    let mut doc = TantivyDocument::default();
+    doc.add_object(field, vals);
+    let num_docs = 132;
+    for _ in 0..num_docs {
+        writer.add_document(doc.clone()).unwrap();
+    }
+    writer.commit().unwrap();
+    let reader = index.reader().unwrap();
+    assert_eq!(reader.searcher().segment_readers().len(), 1);
+    let searcher = reader.searcher();
+    let segment_reader = searcher.segment_reader(0u32);
+    let inv_idx = segment_reader.inverted_index(field).unwrap();
+    let mut term = Term::with_type_and_field(Type::Json, field);
+    let mut json_term_writer = JsonTermWriter::wrap(&mut term, false);
+    json_term_writer.push_path_segment("tenant_id");
+    json_term_writer.close_path_and_set_type(Type::U64);
+    json_term_writer.set_fast_value(75u64);
+    let mut postings = inv_idx
+        .read_postings(
+            &json_term_writer.term(),
+            IndexRecordOption::WithFreqsAndPositions,
+        )
+        .unwrap()
+        .unwrap();
+    assert_eq!(postings.doc(), 0);
+    assert_eq!(postings.term_freq(), 1u32);
+    for i in 1..num_docs {
+        assert_eq!(postings.advance(), i);
+        assert_eq!(postings.term_freq(), 1u32);
+    }
+}

src/fastfield/mod.rs

@@ -131,7 +131,7 @@ mod tests {
         }
         let file = directory.open_read(path).unwrap();
 
-        assert_eq!(file.len(), 105);
+        assert_eq!(file.len(), 80);
         let fast_field_readers = FastFieldReaders::open(file, SCHEMA.clone()).unwrap();
         let column = fast_field_readers
             .u64("field")
@@ -181,7 +181,7 @@ mod tests {
             write.terminate().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 133);
+        assert_eq!(file.len(), 108);
         let fast_field_readers = FastFieldReaders::open(file, SCHEMA.clone()).unwrap();
         let col = fast_field_readers
             .u64("field")
@@ -214,7 +214,7 @@ mod tests {
             write.terminate().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 106);
+        assert_eq!(file.len(), 81);
         let fast_field_readers = FastFieldReaders::open(file, SCHEMA.clone()).unwrap();
         let fast_field_reader = fast_field_readers
             .u64("field")
@@ -246,7 +246,7 @@ mod tests {
             write.terminate().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 4501);
+        assert_eq!(file.len(), 4476);
         {
             let fast_field_readers = FastFieldReaders::open(file, SCHEMA.clone()).unwrap();
             let col = fast_field_readers
@@ -279,7 +279,7 @@ mod tests {
             write.terminate().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 277);
+        assert_eq!(file.len(), 252);
 
         {
             let fast_field_readers = FastFieldReaders::open(file, schema).unwrap();
@@ -773,7 +773,7 @@ mod tests {
             write.terminate().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 114);
+        assert_eq!(file.len(), 84);
         let fast_field_readers = FastFieldReaders::open(file, schema).unwrap();
         let bool_col = fast_field_readers.bool("field_bool").unwrap();
         assert_eq!(bool_col.first(0), Some(true));
@@ -805,7 +805,7 @@ mod tests {
             write.terminate().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 126);
+        assert_eq!(file.len(), 96);
         let readers = FastFieldReaders::open(file, schema).unwrap();
         let bool_col = readers.bool("field_bool").unwrap();
         for i in 0..25 {
@@ -830,7 +830,7 @@ mod tests {
             write.terminate().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 116);
+        assert_eq!(file.len(), 86);
         let fastfield_readers = FastFieldReaders::open(file, schema).unwrap();
         let col = fastfield_readers.bool("field_bool").unwrap();
         assert_eq!(col.first(0), None);
@@ -1288,11 +1288,18 @@ mod tests {
         index_writer.commit().unwrap();
         let searcher = index.reader().unwrap().searcher();
         let fast_field_reader = searcher.segment_reader(0u32).fast_fields();
+        // Supported for now, maybe dropped in the future.
         let column = fast_field_reader
             .column_opt::<i64>("jsonfield.attr.age")
             .unwrap()
             .unwrap();
         let vals: Vec<i64> = column.values_for_doc(0u32).collect();
         assert_eq!(&vals, &[33]);
+        let column = fast_field_reader
+            .column_opt::<i64>("jsonfield\\.attr.age")
+            .unwrap()
+            .unwrap();
+        let vals: Vec<i64> = column.values_for_doc(0u32).collect();
+        assert_eq!(&vals, &[33]);
     }
 }

src/fastfield/writer.rs

@@ -238,13 +238,17 @@ impl FastFieldsWriter {
         mut self,
         wrt: &mut dyn io::Write,
         doc_id_map_opt: Option<&DocIdMapping>,
-    ) -> io::Result<()> {
+    ) -> io::Result<Vec<(String, Type)>> {
         let num_docs = self.num_docs;
         let old_to_new_row_ids =
             doc_id_map_opt.map(|doc_id_mapping| doc_id_mapping.old_to_new_ids());
-        self.columnar_writer
+        let columns = self
+            .columnar_writer
             .serialize(num_docs, old_to_new_row_ids, wrt)?;
-        Ok(())
+        Ok(columns
+            .into_iter()
+            .map(|(field_name, column)| (field_name.to_string(), column.into()))
+            .collect())
     }
 }
 

src/field_list/mod.rs

@@ -0,0 +1,369 @@
+//! The list of fields that are stored in a `tantivy` `Index`.
+
+use std::collections::HashSet;
+use std::io::{self, ErrorKind, Read};
+
+use columnar::ColumnType;
+use common::TinySet;
+use fnv::FnvHashMap;
+
+use crate::indexer::path_to_unordered_id::OrderedPathId;
+use crate::json_utils::json_path_sep_to_dot;
+use crate::postings::IndexingContext;
+use crate::schema::{Field, Schema, Type};
+use crate::{merge_field_meta_data, FieldMetadata, Term};
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash)]
+pub(crate) struct FieldConfig {
+    pub typ: Type,
+    pub indexed: bool,
+    pub stored: bool,
+    pub fast: bool,
+}
+
+impl FieldConfig {
+    fn serialize(&self) -> [u8; 2] {
+        let typ = self.typ.to_code();
+        let flags = (self.indexed as u8) << 2 | (self.stored as u8) << 1 | (self.fast as u8);
+        [typ, flags]
+    }
+    fn deserialize_from(data: [u8; 2]) -> io::Result<FieldConfig> {
+        let typ = Type::from_code(data[0]).ok_or_else(|| {
+            io::Error::new(
+                ErrorKind::InvalidData,
+                format!("could not deserialize type {}", data[0]),
+            )
+        })?;
+
+        let data = data[1];
+        let indexed = (data & 0b100) != 0;
+        let stored = (data & 0b010) != 0;
+        let fast = (data & 0b001) != 0;
+
+        Ok(FieldConfig {
+            typ,
+            indexed,
+            stored,
+            fast,
+        })
+    }
+}
+/// Serializes the split fields.
+pub(crate) fn serialize_segment_fields(
+    ctx: IndexingContext,
+    wrt: &mut dyn io::Write,
+    schema: &Schema,
+    unordered_id_to_ordered_id: &[(OrderedPathId, TinySet)],
+    mut columns: Vec<(String, Type)>,
+) -> crate::Result<()> {
+    let mut field_list_set: HashSet<(Field, OrderedPathId, TinySet)> = HashSet::default();
+    let mut encoded_fields = Vec::new();
+    let mut map_to_canonical = FnvHashMap::default();
+
+    // Replace unordered ids by ordered ids to be able to sort
+    let ordered_id_to_path = ctx.path_to_unordered_id.ordered_id_to_path();
+
+    for (key, _addr) in ctx.term_index.iter() {
+        let field = Term::wrap(key).field();
+        let field_entry = schema.get_field_entry(field);
+        if field_entry.field_type().value_type() == Type::Json {
+            let byte_range_unordered_id = 5..5 + 4;
+            let unordered_id =
+                u32::from_be_bytes(key[byte_range_unordered_id.clone()].try_into().unwrap());
+            let (path_id, typ_code_bitvec) = unordered_id_to_ordered_id[unordered_id as usize];
+            if !field_list_set.contains(&(field, path_id, typ_code_bitvec)) {
+                field_list_set.insert((field, path_id, typ_code_bitvec));
+                let mut build_path = |field_name: &str, mut json_path: String| {
+                    // In this case we need to map the potential fast field to the field name
+                    // accepted by the query parser.
+                    let create_canonical =
+                        !field_entry.is_expand_dots_enabled() && json_path.contains('.');
+                    if create_canonical {
+                        // Without expand dots enabled dots need to be escaped.
+                        let escaped_json_path = json_path.replace('.', "\\.");
+                        let full_path = format!("{}.{}", field_name, escaped_json_path);
+                        let full_path_unescaped = format!("{}.{}", field_name, &json_path);
+                        map_to_canonical.insert(full_path_unescaped, full_path.to_string());
+                        full_path
+                    } else {
+                        // With expand dots enabled, we can use '.' instead of '\u{1}'.
+                        json_path_sep_to_dot(&mut json_path);
+                        format!("{}.{}", field_name, json_path)
+                    }
+                };
+
+                let path = build_path(
+                    field_entry.name(),
+                    ordered_id_to_path[path_id.path_id() as usize].to_string(), /* String::from_utf8(key[5..].to_vec()).unwrap(), */
+                );
+                encoded_fields.push((path, typ_code_bitvec));
+            }
+        }
+    }
+
+    let mut indexed_fields: Vec<FieldMetadata> = Vec::new();
+    for (_field, field_entry) in schema.fields() {
+        let field_name = field_entry.name().to_string();
+        let is_indexed = field_entry.is_indexed();
+
+        let is_json = field_entry.field_type().value_type() == Type::Json;
+        if is_indexed && !is_json {
+            indexed_fields.push(FieldMetadata {
+                indexed: true,
+                stored: false,
+                field_name: field_name.to_string(),
+                fast: false,
+                typ: field_entry.field_type().value_type(),
+            });
+        }
+    }
+    for (field_name, field_type_set) in encoded_fields {
+        for field_type in field_type_set {
+            let column_type = ColumnType::try_from_code(field_type as u8).unwrap();
+            indexed_fields.push(FieldMetadata {
+                indexed: true,
+                stored: false,
+                field_name: field_name.to_string(),
+                fast: false,
+                typ: Type::from(column_type),
+            });
+        }
+    }
+    let mut fast_fields: Vec<FieldMetadata> = columns
+        .iter_mut()
+        .map(|(field_name, typ)| {
+            json_path_sep_to_dot(field_name);
+            // map to canonical path, to avoid similar but different entries.
+            // Eventually we should just accept '.' seperated for all cases.
+            let field_name = map_to_canonical
+                .get(field_name)
+                .unwrap_or(field_name)
+                .to_string();
+            FieldMetadata {
+                indexed: false,
+                stored: false,
+                field_name,
+                fast: true,
+                typ: *typ,
+            }
+        })
+        .collect();
+    // Since the type is encoded differently in the fast field and in the inverted index,
+    // the order of the fields is not guaranteed to be the same. Therefore, we sort the fields.
+    // If we are sure that the order is the same, we can remove this sort.
+    indexed_fields.sort_unstable();
+    fast_fields.sort_unstable();
+    let merged = merge_field_meta_data(vec![indexed_fields, fast_fields], schema);
+    let out = serialize_split_fields(&merged);
+    wrt.write_all(&out)?;
+
+    Ok(())
+}
+
+/// Serializes the Split fields.
+///
+/// `fields_metadata` has to be sorted.
+pub fn serialize_split_fields(fields_metadata: &[FieldMetadata]) -> Vec<u8> {
+    // ensure that fields_metadata is strictly sorted.
+    debug_assert!(fields_metadata.windows(2).all(|w| w[0] < w[1]));
+    let mut payload = Vec::new();
+    // Write Num Fields
+    let length = fields_metadata.len() as u32;
+    payload.extend_from_slice(&length.to_le_bytes());
+
+    for field_metadata in fields_metadata {
+        write_field(field_metadata, &mut payload);
+    }
+    let compression_level = 3;
+    let payload_compressed = zstd::stream::encode_all(&mut &payload[..], compression_level)
+        .expect("zstd encoding failed");
+    let mut out = Vec::new();
+    // Write Header -- Format Version
+    let format_version = 1u8;
+    out.push(format_version);
+    // Write Payload
+    out.extend_from_slice(&payload_compressed);
+    out
+}
+
+fn write_field(field_metadata: &FieldMetadata, out: &mut Vec<u8>) {
+    let field_config = FieldConfig {
+        typ: field_metadata.typ,
+        indexed: field_metadata.indexed,
+        stored: field_metadata.stored,
+        fast: field_metadata.fast,
+    };
+
+    // Write Config 2 bytes
+    out.extend_from_slice(&field_config.serialize());
+    let str_length = field_metadata.field_name.len() as u16;
+    // Write String length 2 bytes
+    out.extend_from_slice(&str_length.to_le_bytes());
+    out.extend_from_slice(field_metadata.field_name.as_bytes());
+}
+
+/// Reads a fixed number of bytes into an array and returns the array.
+fn read_exact_array<R: Read, const N: usize>(reader: &mut R) -> io::Result<[u8; N]> {
+    let mut buffer = [0u8; N];
+    reader.read_exact(&mut buffer)?;
+    Ok(buffer)
+}
+
+/// Reads the Split fields from a zstd compressed stream of bytes
+pub fn read_split_fields<R: Read>(
+    mut reader: R,
+) -> io::Result<impl Iterator<Item = io::Result<FieldMetadata>>> {
+    let format_version = read_exact_array::<_, 1>(&mut reader)?[0];
+    assert_eq!(format_version, 1);
+    let reader = zstd::Decoder::new(reader)?;
+    read_split_fields_from_zstd(reader)
+}
+
+fn read_field<R: Read>(reader: &mut R) -> io::Result<FieldMetadata> {
+    // Read FieldConfig (2 bytes)
+    let config_bytes = read_exact_array::<_, 2>(reader)?;
+    let field_config = FieldConfig::deserialize_from(config_bytes)?; // Assuming this returns a Result
+
+    // Read field name length and the field name
+    let name_len = u16::from_le_bytes(read_exact_array::<_, 2>(reader)?) as usize;
+
+    let mut data = vec![0; name_len];
+    reader.read_exact(&mut data)?;
+
+    let field_name = String::from_utf8(data).map_err(|err| {
+        io::Error::new(
+            ErrorKind::InvalidData,
+            format!(
+                "Encountered invalid utf8 when deserializing field name: {}",
+                err
+            ),
+        )
+    })?;
+    Ok(FieldMetadata {
+        field_name,
+        typ: field_config.typ,
+        indexed: field_config.indexed,
+        stored: field_config.stored,
+        fast: field_config.fast,
+    })
+}
+
+/// Reads the Split fields from a stream of bytes
+fn read_split_fields_from_zstd<R: Read>(
+    mut reader: R,
+) -> io::Result<impl Iterator<Item = io::Result<FieldMetadata>>> {
+    let mut num_fields = u32::from_le_bytes(read_exact_array::<_, 4>(&mut reader)?);
+
+    Ok(std::iter::from_fn(move || {
+        if num_fields == 0 {
+            return None;
+        }
+        num_fields -= 1;
+
+        Some(read_field(&mut reader))
+    }))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn field_config_deser_test() {
+        let field_config = FieldConfig {
+            typ: Type::Str,
+            indexed: true,
+            stored: false,
+            fast: true,
+        };
+        let serialized = field_config.serialize();
+        let deserialized = FieldConfig::deserialize_from(serialized).unwrap();
+        assert_eq!(field_config, deserialized);
+    }
+    #[test]
+    fn write_read_field_test() {
+        for typ in Type::iter_values() {
+            let field_metadata = FieldMetadata {
+                field_name: "test".to_string(),
+                typ,
+                indexed: true,
+                stored: true,
+                fast: true,
+            };
+            let mut out = Vec::new();
+            write_field(&field_metadata, &mut out);
+            let deserialized = read_field(&mut &out[..]).unwrap();
+            assert_eq!(field_metadata, deserialized);
+        }
+        let field_metadata = FieldMetadata {
+            field_name: "test".to_string(),
+            typ: Type::Str,
+            indexed: false,
+            stored: true,
+            fast: true,
+        };
+        let mut out = Vec::new();
+        write_field(&field_metadata, &mut out);
+        let deserialized = read_field(&mut &out[..]).unwrap();
+        assert_eq!(field_metadata, deserialized);
+
+        let field_metadata = FieldMetadata {
+            field_name: "test".to_string(),
+            typ: Type::Str,
+            indexed: false,
+            stored: false,
+            fast: true,
+        };
+        let mut out = Vec::new();
+        write_field(&field_metadata, &mut out);
+        let deserialized = read_field(&mut &out[..]).unwrap();
+        assert_eq!(field_metadata, deserialized);
+
+        let field_metadata = FieldMetadata {
+            field_name: "test".to_string(),
+            typ: Type::Str,
+            indexed: true,
+            stored: false,
+            fast: false,
+        };
+        let mut out = Vec::new();
+        write_field(&field_metadata, &mut out);
+        let deserialized = read_field(&mut &out[..]).unwrap();
+        assert_eq!(field_metadata, deserialized);
+    }
+    #[test]
+    fn write_split_fields_test() {
+        let fields_metadata = vec![
+            FieldMetadata {
+                field_name: "test".to_string(),
+                typ: Type::Str,
+                indexed: true,
+                stored: true,
+                fast: true,
+            },
+            FieldMetadata {
+                field_name: "test2".to_string(),
+                typ: Type::Str,
+                indexed: true,
+                stored: false,
+                fast: false,
+            },
+            FieldMetadata {
+                field_name: "test3".to_string(),
+                typ: Type::U64,
+                indexed: true,
+                stored: false,
+                fast: true,
+            },
+        ];
+
+        let out = serialize_split_fields(&fields_metadata);
+
+        let deserialized: Vec<FieldMetadata> = read_split_fields(&mut &out[..])
+            .unwrap()
+            .map(|el| el.unwrap())
+            .collect();
+
+        assert_eq!(fields_metadata, deserialized);
+    }
+}

src/indexer/merger.rs

@@ -1,3 +1,4 @@
+use std::io::Write;
 use std::sync::Arc;
 
 use columnar::{
@@ -13,6 +14,7 @@ use crate::directory::WritePtr;
 use crate::docset::{DocSet, TERMINATED};
 use crate::error::DataCorruption;
 use crate::fastfield::{AliveBitSet, FastFieldNotAvailableError};
+use crate::field_list::serialize_split_fields;
 use crate::fieldnorm::{FieldNormReader, FieldNormReaders, FieldNormsSerializer, FieldNormsWriter};
 use crate::indexer::doc_id_mapping::{MappingType, SegmentDocIdMapping};
 use crate::indexer::SegmentSerializer;
@@ -21,8 +23,8 @@ use crate::schema::{value_type_to_column_type, Field, FieldType, Schema};
 use crate::store::StoreWriter;
 use crate::termdict::{TermMerger, TermOrdinal};
 use crate::{
-    DocAddress, DocId, IndexSettings, IndexSortByField, InvertedIndexReader, Order,
-    SegmentComponent, SegmentOrdinal,
+    merge_field_meta_data, DocAddress, DocId, FieldMetadata, IndexSettings, IndexSortByField,
+    InvertedIndexReader, Order, SegmentComponent, SegmentOrdinal,
 };
 
 /// Segment's max doc must be `< MAX_DOC_LIMIT`.
@@ -255,6 +257,19 @@ impl IndexMerger {
         Ok(())
     }
 
+    fn write_field_list(&self, list_field_wrt: &mut WritePtr) -> crate::Result<()> {
+        let field_metadatas: Vec<Vec<FieldMetadata>> = self
+            .readers
+            .iter()
+            .map(|reader| reader.fields_metadata())
+            .collect::<crate::Result<Vec<_>>>()?;
+        let merged = merge_field_meta_data(field_metadatas, &self.schema);
+        let out = serialize_split_fields(&merged);
+        list_field_wrt.write_all(&out)?;
+
+        Ok(())
+    }
+
     fn write_fast_fields(
         &self,
         fast_field_wrt: &mut WritePtr,
@@ -552,7 +567,41 @@ impl IndexMerger {
                 continue;
             }
 
-            field_serializer.new_term(term_bytes, total_doc_freq)?;
+            // This should never happen as we early exited for total_doc_freq == 0.
+            assert!(!segment_postings_containing_the_term.is_empty());
+
+            let has_term_freq = {
+                let has_term_freq = !segment_postings_containing_the_term[0]
+                    .1
+                    .block_cursor
+                    .freqs()
+                    .is_empty();
+                for (_, postings) in &segment_postings_containing_the_term[1..] {
+                    // This may look at a strange way to test whether we have term freq or not.
+                    // With JSON object, the schema is not sufficient to know whether a term
+                    // has its term frequency encoded or not:
+                    // strings may have term frequencies, while number terms never have one.
+                    //
+                    // Ideally, we should have burnt one bit of two in the `TermInfo`.
+                    // However, we preferred not changing the codec too much and detect this
+                    // instead by
+                    // - looking at the size of the skip data for bitpacked blocks
+                    // - observing the absence of remaining data after reading the docs for vint
+                    // blocks.
+                    //
+                    // Overall the reliable way to know if we have actual frequencies loaded or not
+                    // is to check whether the actual decoded array is empty or not.
+                    if has_term_freq != !postings.block_cursor.freqs().is_empty() {
+                        return Err(DataCorruption::comment_only(
+                            "Term freqs are inconsistent across segments",
+                        )
+                        .into());
+                    }
+                }
+                has_term_freq
+            };
+
+            field_serializer.new_term(term_bytes, total_doc_freq, has_term_freq)?;
 
             // We can now serialize this postings, by pushing each document to the
             // postings serializer.
@@ -567,8 +616,13 @@ impl IndexMerger {
                     if let Some(remapped_doc_id) = old_to_new_doc_id[doc as usize] {
                         // we make sure to only write the term if
                         // there is at least one document.
-                        let term_freq = segment_postings.term_freq();
-                        segment_postings.positions(&mut positions_buffer);
+                        let term_freq = if has_term_freq {
+                            segment_postings.positions(&mut positions_buffer);
+                            segment_postings.term_freq()
+                        } else {
+                            0u32
+                        };
+
                         // if doc_id_mapping exists, the doc_ids are reordered, they are
                         // not just stacked. The field serializer expects monotonically increasing
                         // doc_ids, so we collect and sort them first, before writing.
@@ -734,6 +788,7 @@ impl IndexMerger {
         self.write_storable_fields(serializer.get_store_writer(), &doc_id_mapping)?;
         debug!("write-fastfields");
         self.write_fast_fields(serializer.get_fast_field_write(), doc_id_mapping)?;
+        self.write_field_list(serializer.get_field_list_write())?;
 
         debug!("close-serializer");
         serializer.close()?;

src/indexer/mod.rs

@@ -59,10 +59,13 @@ type AddBatchReceiver<D> = channel::Receiver<AddBatch<D>>;
 #[cfg(test)]
 mod tests_mmap {
 
-    use crate::collector::Count;
-    use crate::query::QueryParser;
-    use crate::schema::{JsonObjectOptions, Schema, Type, TEXT};
-    use crate::{Index, IndexWriter, Term};
+    use crate::aggregation::agg_req::Aggregations;
+    use crate::aggregation::agg_result::AggregationResults;
+    use crate::aggregation::AggregationCollector;
+    use crate::collector::{Count, TopDocs};
+    use crate::query::{AllQuery, QueryParser};
+    use crate::schema::{JsonObjectOptions, Schema, Type, FAST, INDEXED, STORED, TEXT};
+    use crate::{FieldMetadata, Index, IndexWriter, Term};
 
     #[test]
     fn test_advance_delete_bug() -> crate::Result<()> {
@@ -173,8 +176,7 @@ mod tests_mmap {
     #[test]
     fn test_json_field_list_fields() {
         let mut schema_builder = Schema::builder();
-        let json_options: JsonObjectOptions =
-            JsonObjectOptions::from(TEXT).set_expand_dots_enabled();
+        let json_options: JsonObjectOptions = JsonObjectOptions::from(TEXT);
         let json_field = schema_builder.add_json_field("json", json_options);
         let index = Index::create_in_ram(schema_builder.build());
         let mut index_writer = index.writer_for_tests().unwrap();
@@ -193,9 +195,9 @@ mod tests_mmap {
         let reader = &searcher.segment_readers()[0];
         let inverted_index = reader.inverted_index(json_field).unwrap();
         assert_eq!(
-            inverted_index.list_fields().unwrap(),
+            inverted_index.list_encoded_fields().unwrap(),
             [
-                ("k8s\u{1}container\u{1}name".to_string(), Type::Str),
+                ("k8s.container.name".to_string(), Type::Str),
                 ("sub\u{1}a".to_string(), Type::I64),
                 ("sub\u{1}b".to_string(), Type::I64),
                 ("suber\u{1}a".to_string(), Type::I64),
@@ -205,4 +207,240 @@ mod tests_mmap {
             ]
         );
     }
+
+    #[test]
+    fn test_json_fields_metadata_expanded_dots_one_segment() {
+        test_json_fields_metadata(true, true);
+    }
+    #[test]
+    fn test_json_fields_metadata_expanded_dots_multi_segment() {
+        test_json_fields_metadata(true, false);
+    }
+    #[test]
+    fn test_json_fields_metadata_no_expanded_dots_one_segment() {
+        test_json_fields_metadata(false, true);
+    }
+    #[test]
+    fn test_json_fields_metadata_no_expanded_dots_multi_segment() {
+        test_json_fields_metadata(false, false);
+    }
+
+    fn test_json_fields_metadata(expanded_dots: bool, one_segment: bool) {
+        use pretty_assertions::assert_eq;
+        let mut schema_builder = Schema::builder();
+        let json_options: JsonObjectOptions =
+            JsonObjectOptions::from(TEXT).set_fast(None).set_stored();
+        let json_options = if expanded_dots {
+            json_options.set_expand_dots_enabled()
+        } else {
+            json_options
+        };
+        schema_builder.add_json_field("json.confusing", json_options.clone());
+        let json_field = schema_builder.add_json_field("json.shadow", json_options.clone());
+        let json_field2 = schema_builder.add_json_field("json", json_options.clone());
+        schema_builder.add_json_field("empty_json", json_options);
+        let number_field = schema_builder.add_u64_field("numbers", FAST);
+        schema_builder.add_u64_field("empty", FAST | INDEXED | STORED);
+        let index = Index::create_in_ram(schema_builder.build());
+        let mut index_writer = index.writer_for_tests().unwrap();
+        let json =
+            serde_json::json!({"k8s.container.name": "a", "val": "a", "sub": {"a": 1, "b": 1}});
+        index_writer.add_document(doc!(json_field=>json)).unwrap();
+        let json =
+            serde_json::json!({"k8s.container.name": "a", "val": "a", "suber": {"a": 1, "b": 1}});
+        if !one_segment {
+            index_writer.commit().unwrap();
+        }
+        index_writer.add_document(doc!(json_field=>json)).unwrap();
+        let json = serde_json::json!({"k8s.container.name": "a", "k8s.container.name": "a", "val": "a", "suber": {"a": "a", "b": 1}});
+        index_writer
+            .add_document(doc!(number_field => 50u64, json_field=>json, json_field2=>json!({"shadow": {"val": "a"}})))
+            .unwrap();
+        index_writer.commit().unwrap();
+        let reader = index.reader().unwrap();
+
+        let searcher = reader.searcher();
+        assert_eq!(searcher.num_docs(), 3);
+
+        let fields_metadata = index.fields_metadata().unwrap();
+        assert_eq!(
+            fields_metadata,
+            [
+                FieldMetadata {
+                    field_name: "empty".to_string(),
+                    indexed: true,
+                    stored: true,
+                    fast: true,
+                    typ: Type::U64
+                },
+                FieldMetadata {
+                    field_name: if expanded_dots {
+                        "json.shadow.k8s.container.name".to_string()
+                    } else {
+                        "json.shadow.k8s\\.container\\.name".to_string()
+                    },
+                    indexed: true,
+                    stored: true,
+                    fast: true,
+                    typ: Type::Str
+                },
+                FieldMetadata {
+                    field_name: "json.shadow.sub.a".to_string(),
+                    indexed: true,
+                    stored: true,
+                    fast: true,
+                    typ: Type::I64
+                },
+                FieldMetadata {
+                    field_name: "json.shadow.sub.b".to_string(),
+                    indexed: true,
+                    stored: true,
+                    fast: true,
+                    typ: Type::I64
+                },
+                FieldMetadata {
+                    field_name: "json.shadow.suber.a".to_string(),
+                    indexed: true,
+                    stored: true,
+                    fast: true,
+                    typ: Type::I64
+                },
+                FieldMetadata {
+                    field_name: "json.shadow.suber.a".to_string(),
+                    indexed: true,
+                    stored: true,
+                    fast: true,
+                    typ: Type::Str
+                },
+                FieldMetadata {
+                    field_name: "json.shadow.suber.b".to_string(),
+                    indexed: true,
+                    stored: true,
+                    fast: true,
+                    typ: Type::I64
+                },
+                FieldMetadata {
+                    field_name: "json.shadow.val".to_string(),
+                    indexed: true,
+                    stored: true,
+                    fast: true,
+                    typ: Type::Str
+                },
+                FieldMetadata {
+                    field_name: "numbers".to_string(),
+                    indexed: false,
+                    stored: false,
+                    fast: true,
+                    typ: Type::U64
+                }
+            ]
+        );
+        let query_parser = QueryParser::for_index(&index, vec![]);
+        // Test if returned field name can be queried
+        for indexed_field in fields_metadata.iter().filter(|meta| meta.indexed) {
+            let val = if indexed_field.typ == Type::Str {
+                "a"
+            } else {
+                "1"
+            };
+            let query_str = &format!("{}:{}", indexed_field.field_name, val);
+            let query = query_parser.parse_query(query_str).unwrap();
+            let count_docs = searcher.search(&*query, &TopDocs::with_limit(2)).unwrap();
+            if indexed_field.field_name.contains("empty") || indexed_field.typ == Type::Json {
+                assert_eq!(count_docs.len(), 0);
+            } else {
+                assert!(!count_docs.is_empty(), "{}", indexed_field.field_name);
+            }
+        }
+        // Test if returned field name can be used for aggregation
+        for fast_field in fields_metadata.iter().filter(|meta| meta.fast) {
+            let agg_req_str = json!(
+            {
+              "termagg": {
+                "terms": {
+                  "field": fast_field.field_name,
+                }
+              }
+            });
+
+            let agg_req: Aggregations = serde_json::from_value(agg_req_str).unwrap();
+            let collector = AggregationCollector::from_aggs(agg_req, Default::default());
+            let agg_res: AggregationResults = searcher.search(&AllQuery, &collector).unwrap();
+            let res = serde_json::to_value(agg_res).unwrap();
+            if !fast_field.field_name.contains("empty") && fast_field.typ != Type::Json {
+                assert!(
+                    !res["termagg"]["buckets"].as_array().unwrap().is_empty(),
+                    "{}",
+                    fast_field.field_name
+                );
+            }
+        }
+    }
+
+    #[test]
+    fn test_json_field_shadowing_field_name_bug() {
+        /// This test is only there to display a bug on addressing a field if it gets shadowed
+        /// The issues only occurs if the field name that shadows contains a dot.
+        ///
+        /// Happens independently of the `expand_dots` option. Since that option does not
+        /// affect the field name itself.
+        use pretty_assertions::assert_eq;
+        let mut schema_builder = Schema::builder();
+        let json_options: JsonObjectOptions =
+            JsonObjectOptions::from(TEXT).set_fast(None).set_stored();
+        // let json_options = json_options.set_expand_dots_enabled();
+        let json_field_shadow = schema_builder.add_json_field("json.shadow", json_options.clone());
+        let json_field = schema_builder.add_json_field("json", json_options.clone());
+        let index = Index::create_in_ram(schema_builder.build());
+        let mut index_writer = index.writer_for_tests().unwrap();
+        index_writer
+            .add_document(
+                doc!(json_field_shadow=>json!({"val": "b"}), json_field=>json!({"shadow": {"val": "a"}})),
+            )
+            .unwrap();
+        index_writer.commit().unwrap();
+        let reader = index.reader().unwrap();
+
+        let searcher = reader.searcher();
+
+        let fields_and_vals = vec![
+            // Only way to address or it gets shadowed by `json.shadow` field
+            ("json.shadow\u{1}val".to_string(), "a"), // Succeeds
+            //("json.shadow.val".to_string(), "a"),   // Fails
+            ("json.shadow.val".to_string(), "b"), // Succeeds
+        ];
+
+        let query_parser = QueryParser::for_index(&index, vec![]);
+        // Test if field name can be queried
+        for (indexed_field, val) in fields_and_vals.iter() {
+            let query_str = &format!("{}:{}", indexed_field, val);
+            let query = query_parser.parse_query(query_str).unwrap();
+            let count_docs = searcher.search(&*query, &TopDocs::with_limit(2)).unwrap();
+            assert!(!count_docs.is_empty(), "{}:{}", indexed_field, val);
+        }
+        // Test if field name can be used for aggregation
+        for (field_name, val) in fields_and_vals.iter() {
+            let agg_req_str = json!(
+            {
+              "termagg": {
+                "terms": {
+                  "field": field_name,
+                }
+              }
+            });
+
+            let agg_req: Aggregations = serde_json::from_value(agg_req_str).unwrap();
+            let collector = AggregationCollector::from_aggs(agg_req, Default::default());
+            let agg_res: AggregationResults = searcher.search(&AllQuery, &collector).unwrap();
+            let res = serde_json::to_value(agg_res).unwrap();
+            assert_eq!(
+                res["termagg"]["buckets"].as_array().unwrap()[0]["key"]
+                    .as_str()
+                    .unwrap(),
+                *val,
+                "{}",
+                field_name
+            );
+        }
+    }
 }

src/indexer/path_to_unordered_id.rs

@@ -1,3 +1,5 @@
+use columnar::ColumnType;
+use common::TinySet;
 use fnv::FnvHashMap;
 
 /// `Field` is represented by an unsigned 32-bit integer type.
@@ -24,34 +26,44 @@ impl From<u32> for OrderedPathId {
 
 #[derive(Default)]
 pub(crate) struct PathToUnorderedId {
-    map: FnvHashMap<String, u32>,
+    /// TinySet contains the type codes of the columns in the path.
+    map: FnvHashMap<String, (u32, TinySet)>,
 }
 
 impl PathToUnorderedId {
     #[inline]
-    pub(crate) fn get_or_allocate_unordered_id(&mut self, path: &str) -> u32 {
-        if let Some(id) = self.map.get(path) {
+    pub(crate) fn get_or_allocate_unordered_id(&mut self, path: &str, typ: ColumnType) -> u32 {
+        let code_bit = typ.to_code();
+        if let Some((id, all_codes)) = self.map.get_mut(path) {
+            *all_codes = all_codes.insert(code_bit as u32);
             return *id;
         }
-        self.insert_new_path(path)
+        self.insert_new_path(path, code_bit)
     }
     #[cold]
-    fn insert_new_path(&mut self, path: &str) -> u32 {
+    fn insert_new_path(&mut self, path: &str, typ_code: u8) -> u32 {
         let next_id = self.map.len() as u32;
-        self.map.insert(path.to_string(), next_id);
+        self.map.insert(
+            path.to_string(),
+            (next_id, TinySet::singleton(typ_code as u32)),
+        );
         next_id
     }
 
     /// Retuns ids which reflect the lexical order of the paths.
     ///
     /// The returned vec can be indexed with the unordered id to get the ordered id.
-    pub(crate) fn unordered_id_to_ordered_id(&self) -> Vec<OrderedPathId> {
-        let mut sorted_ids: Vec<(&str, &u32)> =
-            self.map.iter().map(|(k, v)| (k.as_str(), v)).collect();
+    pub(crate) fn unordered_id_to_ordered_id(&self) -> Vec<(OrderedPathId, TinySet)> {
+        let mut sorted_ids: Vec<(&str, (u32, TinySet))> = self
+            .map
+            .iter()
+            .map(|(k, (id, typ_code))| (k.as_str(), (*id, *typ_code)))
+            .collect();
         sorted_ids.sort_unstable_by_key(|(path, _)| *path);
-        let mut result = vec![OrderedPathId::default(); sorted_ids.len()];
-        for (ordered, unordered) in sorted_ids.iter().map(|(_k, v)| v).enumerate() {
-            result[**unordered as usize] = OrderedPathId::from_ordered_id(ordered as u32);
+        let mut result = vec![(OrderedPathId::default(), TinySet::empty()); sorted_ids.len()];
+        for (ordered, (unordered, typ_code)) in sorted_ids.iter().map(|(_k, v)| v).enumerate() {
+            result[*unordered as usize] =
+                (OrderedPathId::from_ordered_id(ordered as u32), *typ_code);
         }
         result
     }
@@ -74,12 +86,12 @@ mod tests {
         let terms = vec!["b", "a", "b", "c"];
         let ids = terms
             .iter()
-            .map(|term| path_to_id.get_or_allocate_unordered_id(term))
+            .map(|term| path_to_id.get_or_allocate_unordered_id(term, ColumnType::Str))
             .collect::<Vec<u32>>();
         assert_eq!(ids, vec![0, 1, 0, 2]);
         let ordered_ids = ids
             .iter()
-            .map(|id| path_to_id.unordered_id_to_ordered_id()[*id as usize])
+            .map(|id| path_to_id.unordered_id_to_ordered_id()[*id as usize].0)
             .collect::<Vec<OrderedPathId>>();
         assert_eq!(ordered_ids, vec![1.into(), 0.into(), 1.into(), 2.into()]);
         // Fetch terms

src/indexer/segment_serializer.rs

@@ -12,6 +12,7 @@ pub struct SegmentSerializer {
     segment: Segment,
     pub(crate) store_writer: StoreWriter,
     fast_field_write: WritePtr,
+    field_list_write: WritePtr,
     fieldnorms_serializer: Option<FieldNormsSerializer>,
     postings_serializer: InvertedIndexSerializer,
 }
@@ -49,6 +50,7 @@ impl SegmentSerializer {
         };
 
         let fast_field_write = segment.open_write(SegmentComponent::FastFields)?;
+        let field_list_write = segment.open_write(SegmentComponent::FieldList)?;
 
         let fieldnorms_write = segment.open_write(SegmentComponent::FieldNorms)?;
         let fieldnorms_serializer = FieldNormsSerializer::from_write(fieldnorms_write)?;
@@ -58,6 +60,7 @@ impl SegmentSerializer {
             segment,
             store_writer,
             fast_field_write,
+            field_list_write,
             fieldnorms_serializer: Some(fieldnorms_serializer),
             postings_serializer,
         })
@@ -81,6 +84,11 @@ impl SegmentSerializer {
         &mut self.postings_serializer
     }
 
+    /// Accessor to the ``.
+    pub fn get_field_list_write(&mut self) -> &mut WritePtr {
+        &mut self.field_list_write
+    }
+
     /// Accessor to the `FastFieldSerializer`.
     pub fn get_fast_field_write(&mut self) -> &mut WritePtr {
         &mut self.fast_field_write
@@ -104,6 +112,7 @@ impl SegmentSerializer {
             fieldnorms_serializer.close()?;
         }
         self.fast_field_write.terminate()?;
+        self.field_list_write.terminate()?;
         self.postings_serializer.close()?;
         self.store_writer.close()?;
         Ok(())

src/indexer/segment_writer.rs

@@ -8,6 +8,7 @@ use super::operation::AddOperation;
 use crate::core::json_utils::index_json_values;
 use crate::core::Segment;
 use crate::fastfield::FastFieldsWriter;
+use crate::field_list::serialize_segment_fields;
 use crate::fieldnorm::{FieldNormReaders, FieldNormsWriter};
 use crate::indexer::segment_serializer::SegmentSerializer;
 use crate::postings::{
@@ -443,16 +444,29 @@ fn remap_and_write(
         .segment()
         .open_read(SegmentComponent::FieldNorms)?;
     let fieldnorm_readers = FieldNormReaders::open(fieldnorm_data)?;
+
+    let unordered_id_to_ordered_id = ctx.path_to_unordered_id.unordered_id_to_ordered_id();
+
     serialize_postings(
-        ctx,
-        schema,
+        &ctx,
+        schema.clone(),
         per_field_postings_writers,
         fieldnorm_readers,
         doc_id_map,
+        &unordered_id_to_ordered_id,
         serializer.get_postings_serializer(),
     )?;
     debug!("fastfield-serialize");
-    fast_field_writers.serialize(serializer.get_fast_field_write(), doc_id_map)?;
+    let columns = fast_field_writers.serialize(serializer.get_fast_field_write(), doc_id_map)?;
+
+    let field_list_serializer = serializer.get_field_list_write();
+    serialize_segment_fields(
+        ctx,
+        field_list_serializer,
+        &schema,
+        &unordered_id_to_ordered_id,
+        columns,
+    )?;
 
     // finalize temp docstore and create version, which reflects the doc_id_map
     if let Some(doc_id_map) = doc_id_map {

src/lib.rs

@@ -188,6 +188,7 @@ pub mod aggregation;
 pub mod collector;
 pub mod directory;
 pub mod fastfield;
+pub mod field_list;
 pub mod fieldnorm;
 pub mod positions;
 pub mod postings;
@@ -221,9 +222,9 @@ pub use self::snippet::{Snippet, SnippetGenerator};
 #[doc(hidden)]
 pub use crate::core::json_utils;
 pub use crate::core::{
-    Executor, Index, IndexBuilder, IndexMeta, IndexSettings, IndexSortByField, InvertedIndexReader,
-    Order, Searcher, SearcherGeneration, Segment, SegmentComponent, SegmentId, SegmentMeta,
-    SegmentReader, SingleSegmentIndexWriter,
+    merge_field_meta_data, Executor, FieldMetadata, Index, IndexBuilder, IndexMeta, IndexSettings,
+    IndexSortByField, InvertedIndexReader, Order, Searcher, SearcherGeneration, Segment,
+    SegmentComponent, SegmentId, SegmentMeta, SegmentReader, SingleSegmentIndexWriter,
 };
 pub use crate::directory::Directory;
 pub use crate::indexer::IndexWriter;
@@ -238,7 +239,9 @@ pub use crate::schema::DatePrecision;
 pub use crate::schema::{DateOptions, DateTimePrecision, Document, TantivyDocument, Term};
 
 /// Index format version.
-const INDEX_FORMAT_VERSION: u32 = 6;
+///
+/// Version 7: Add `.fieldlist` file containing the list of fields in a segment.
+const INDEX_FORMAT_VERSION: u32 = 7;
 /// Oldest index format version this tantivy version can read.
 const INDEX_FORMAT_OLDEST_SUPPORTED_VERSION: u32 = 4;
 

src/postings/json_postings_writer.rs

@@ -11,6 +11,10 @@ use crate::schema::{Field, Type, JSON_END_OF_PATH};
 use crate::tokenizer::TokenStream;
 use crate::{DocId, Term};
 
+/// The `JsonPostingsWriter` is odd in that it relies on a hidden contract:
+///
+/// `subscribe` is called directly to index non-text tokens, while
+/// `index_text` is used to index text.
 #[derive(Default)]
 pub(crate) struct JsonPostingsWriter<Rec: Recorder> {
     str_posting_writer: SpecializedPostingsWriter<Rec>,

src/postings/mod.rs

@@ -63,7 +63,7 @@ pub mod tests {
         let mut segment = index.new_segment();
         let mut posting_serializer = InvertedIndexSerializer::open(&mut segment)?;
         let mut field_serializer = posting_serializer.new_field(text_field, 120 * 4, None)?;
-        field_serializer.new_term("abc".as_bytes(), 12u32)?;
+        field_serializer.new_term("abc".as_bytes(), 12u32, true)?;
         for doc_id in 0u32..120u32 {
             let delta_positions = vec![1, 2, 3, 2];
             field_serializer.write_doc(doc_id, 4, &delta_positions);

src/postings/postings_writer.rs

@@ -2,6 +2,7 @@ use std::io;
 use std::marker::PhantomData;
 use std::ops::Range;
 
+use common::TinySet;
 use stacker::Addr;
 
 use crate::fieldnorm::FieldNormReaders;
@@ -46,37 +47,38 @@ fn make_field_partition(
 /// It pushes all term, one field at a time, towards the
 /// postings serializer.
 pub(crate) fn serialize_postings(
-    ctx: IndexingContext,
+    ctx: &IndexingContext,
     schema: Schema,
     per_field_postings_writers: &PerFieldPostingsWriter,
     fieldnorm_readers: FieldNormReaders,
     doc_id_map: Option<&DocIdMapping>,
+    unordered_id_to_ordered_id: &[(OrderedPathId, TinySet)],
     serializer: &mut InvertedIndexSerializer,
 ) -> crate::Result<()> {
     // Replace unordered ids by ordered ids to be able to sort
-    let unordered_id_to_ordered_id: Vec<OrderedPathId> =
-        ctx.path_to_unordered_id.unordered_id_to_ordered_id();
+    let ordered_id_to_path = ctx.path_to_unordered_id.ordered_id_to_path();
 
     let mut term_offsets: Vec<(Field, OrderedPathId, &[u8], Addr)> =
         Vec::with_capacity(ctx.term_index.len());
-    term_offsets.extend(ctx.term_index.iter().map(|(key, addr)| {
+    for (key, addr) in ctx.term_index.iter() {
         let field = Term::wrap(key).field();
-        if schema.get_field_entry(field).field_type().value_type() == Type::Json {
-            let byte_range_path = 5..5 + 4;
-            let unordered_id = u32::from_be_bytes(key[byte_range_path.clone()].try_into().unwrap());
-            let path_id = unordered_id_to_ordered_id[unordered_id as usize];
-            (field, path_id, &key[byte_range_path.end..], addr)
+        let field_entry = schema.get_field_entry(field);
+        if field_entry.field_type().value_type() == Type::Json {
+            let byte_range_unordered_id = 5..5 + 4;
+            let unordered_id =
+                u32::from_be_bytes(key[byte_range_unordered_id.clone()].try_into().unwrap());
+            let (path_id, _typ_code_bitvec) = unordered_id_to_ordered_id[unordered_id as usize];
+            term_offsets.push((field, path_id, &key[byte_range_unordered_id.end..], addr));
         } else {
-            (field, 0.into(), &key[5..], addr)
+            term_offsets.push((field, 0.into(), &key[5..], addr));
         }
-    }));
+    }
     // Sort by field, path, and term
     term_offsets.sort_unstable_by(
         |(field1, path_id1, bytes1, _), (field2, path_id2, bytes2, _)| {
             (field1, path_id1, bytes1).cmp(&(field2, path_id2, bytes2))
         },
     );
-    let ordered_id_to_path = ctx.path_to_unordered_id.ordered_id_to_path();
     let field_offsets = make_field_partition(&term_offsets);
     for (field, byte_offsets) in field_offsets {
         let postings_writer = per_field_postings_writers.get_for_field(field);
@@ -87,7 +89,7 @@ pub(crate) fn serialize_postings(
             &term_offsets[byte_offsets],
             &ordered_id_to_path,
             doc_id_map,
-            &ctx,
+            ctx,
             &mut field_serializer,
         )?;
         field_serializer.close()?;
@@ -194,7 +196,7 @@ impl<Rec: Recorder> SpecializedPostingsWriter<Rec> {
     ) -> io::Result<()> {
         let recorder: Rec = ctx.term_index.read(addr);
         let term_doc_freq = recorder.term_doc_freq().unwrap_or(0u32);
-        serializer.new_term(term, term_doc_freq)?;
+        serializer.new_term(term, term_doc_freq, recorder.has_term_freq())?;
         recorder.serialize(&ctx.arena, doc_id_map, serializer, buffer_lender);
         serializer.close_term()?;
         Ok(())

src/postings/recorder.rs

@@ -79,24 +79,20 @@ pub(crate) trait Recorder: Copy + Default + Send + Sync + 'static {
     ///
     /// Returns `None` if not available.
     fn term_doc_freq(&self) -> Option<u32>;
+
+    #[inline]
+    fn has_term_freq(&self) -> bool {
+        true
+    }
 }
 
 /// Only records the doc ids
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Default)]
 pub struct DocIdRecorder {
     stack: ExpUnrolledLinkedList,
     current_doc: DocId,
 }
 
-impl Default for DocIdRecorder {
-    fn default() -> Self {
-        DocIdRecorder {
-            stack: ExpUnrolledLinkedList::default(),
-            current_doc: u32::MAX,
-        }
-    }
-}
-
 impl Recorder for DocIdRecorder {
     #[inline]
     fn current_doc(&self) -> DocId {
@@ -105,8 +101,9 @@ impl Recorder for DocIdRecorder {
 
     #[inline]
     fn new_doc(&mut self, doc: DocId, arena: &mut MemoryArena) {
+        let delta = doc - self.current_doc;
         self.current_doc = doc;
-        self.stack.writer(arena).write_u32_vint(doc);
+        self.stack.writer(arena).write_u32_vint(delta);
     }
 
     #[inline]
@@ -123,21 +120,20 @@ impl Recorder for DocIdRecorder {
         buffer_lender: &mut BufferLender,
     ) {
         let (buffer, doc_ids) = buffer_lender.lend_all();
-        self.stack.read_to_end(arena, buffer);
         // TODO avoid reading twice.
+        self.stack.read_to_end(arena, buffer);
         if let Some(doc_id_map) = doc_id_map {
-            doc_ids.extend(
-                VInt32Reader::new(&buffer[..])
-                    .map(|old_doc_id| doc_id_map.get_new_doc_id(old_doc_id)),
-            );
+            let iter = get_sum_reader(VInt32Reader::new(&buffer[..]));
+            doc_ids.extend(iter.map(|old_doc_id| doc_id_map.get_new_doc_id(old_doc_id)));
             doc_ids.sort_unstable();
 
             for doc in doc_ids {
                 serializer.write_doc(*doc, 0u32, &[][..]);
             }
         } else {
-            for doc in VInt32Reader::new(&buffer[..]) {
-                serializer.write_doc(doc, 0u32, &[][..]);
+            let iter = get_sum_reader(VInt32Reader::new(&buffer[..]));
+            for doc_id in iter {
+                serializer.write_doc(doc_id, 0u32, &[][..]);
             }
         }
     }
@@ -145,6 +141,19 @@ impl Recorder for DocIdRecorder {
     fn term_doc_freq(&self) -> Option<u32> {
         None
     }
+
+    fn has_term_freq(&self) -> bool {
+        false
+    }
+}
+
+/// Takes an Iterator of delta encoded elements and returns an iterator
+/// that yields the sum of the elements.
+fn get_sum_reader(iter: impl Iterator<Item = u32>) -> impl Iterator<Item = u32> {
+    iter.scan(0, |state, delta| {
+        *state += delta;
+        Some(*state)
+    })
 }
 
 /// Recorder encoding document ids, and term frequencies
@@ -164,9 +173,10 @@ impl Recorder for TermFrequencyRecorder {
 
     #[inline]
     fn new_doc(&mut self, doc: DocId, arena: &mut MemoryArena) {
+        let delta = doc - self.current_doc;
         self.term_doc_freq += 1;
         self.current_doc = doc;
-        self.stack.writer(arena).write_u32_vint(doc);
+        self.stack.writer(arena).write_u32_vint(delta);
     }
 
     #[inline]
@@ -193,9 +203,12 @@ impl Recorder for TermFrequencyRecorder {
         let mut u32_it = VInt32Reader::new(&buffer[..]);
         if let Some(doc_id_map) = doc_id_map {
             let mut doc_id_and_tf = vec![];
-            while let Some(old_doc_id) = u32_it.next() {
+            let mut prev_doc = 0;
+            while let Some(delta_doc_id) = u32_it.next() {
+                let doc_id = prev_doc + delta_doc_id;
+                prev_doc = doc_id;
                 let term_freq = u32_it.next().unwrap_or(self.current_tf);
-                doc_id_and_tf.push((doc_id_map.get_new_doc_id(old_doc_id), term_freq));
+                doc_id_and_tf.push((doc_id_map.get_new_doc_id(doc_id), term_freq));
             }
             doc_id_and_tf.sort_unstable_by_key(|&(doc_id, _)| doc_id);
 
@@ -203,9 +216,12 @@ impl Recorder for TermFrequencyRecorder {
                 serializer.write_doc(doc_id, tf, &[][..]);
             }
         } else {
-            while let Some(doc) = u32_it.next() {
+            let mut prev_doc = 0;
+            while let Some(delta_doc_id) = u32_it.next() {
+                let doc_id = prev_doc + delta_doc_id;
+                prev_doc = doc_id;
                 let term_freq = u32_it.next().unwrap_or(self.current_tf);
-                serializer.write_doc(doc, term_freq, &[][..]);
+                serializer.write_doc(doc_id, term_freq, &[][..]);
             }
         }
     }
@@ -216,23 +232,13 @@ impl Recorder for TermFrequencyRecorder {
 }
 
 /// Recorder encoding term frequencies as well as positions.
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Default)]
 pub struct TfAndPositionRecorder {
     stack: ExpUnrolledLinkedList,
     current_doc: DocId,
     term_doc_freq: u32,
 }
 
-impl Default for TfAndPositionRecorder {
-    fn default() -> Self {
-        TfAndPositionRecorder {
-            stack: ExpUnrolledLinkedList::default(),
-            current_doc: u32::MAX,
-            term_doc_freq: 0u32,
-        }
-    }
-}
-
 impl Recorder for TfAndPositionRecorder {
     #[inline]
     fn current_doc(&self) -> DocId {
@@ -241,9 +247,10 @@ impl Recorder for TfAndPositionRecorder {
 
     #[inline]
     fn new_doc(&mut self, doc: DocId, arena: &mut MemoryArena) {
+        let delta = doc - self.current_doc;
         self.current_doc = doc;
         self.term_doc_freq += 1u32;
-        self.stack.writer(arena).write_u32_vint(doc);
+        self.stack.writer(arena).write_u32_vint(delta);
     }
 
     #[inline]
@@ -269,7 +276,10 @@ impl Recorder for TfAndPositionRecorder {
         self.stack.read_to_end(arena, buffer_u8);
         let mut u32_it = VInt32Reader::new(&buffer_u8[..]);
         let mut doc_id_and_positions = vec![];
-        while let Some(doc) = u32_it.next() {
+        let mut prev_doc = 0;
+        while let Some(delta_doc_id) = u32_it.next() {
+            let doc_id = prev_doc + delta_doc_id;
+            prev_doc = doc_id;
             let mut prev_position_plus_one = 1u32;
             buffer_positions.clear();
             loop {
@@ -287,9 +297,9 @@ impl Recorder for TfAndPositionRecorder {
             if let Some(doc_id_map) = doc_id_map {
                 // this simple variant to remap may consume to much memory
                 doc_id_and_positions
-                    .push((doc_id_map.get_new_doc_id(doc), buffer_positions.to_vec()));
+                    .push((doc_id_map.get_new_doc_id(doc_id), buffer_positions.to_vec()));
             } else {
-                serializer.write_doc(doc, buffer_positions.len() as u32, buffer_positions);
+                serializer.write_doc(doc_id, buffer_positions.len() as u32, buffer_positions);
             }
         }
         if doc_id_map.is_some() {

src/postings/segment_postings.rs

@@ -71,7 +71,7 @@ impl SegmentPostings {
         {
             let mut postings_serializer =
                 PostingsSerializer::new(&mut buffer, 0.0, IndexRecordOption::Basic, None);
-            postings_serializer.new_term(docs.len() as u32);
+            postings_serializer.new_term(docs.len() as u32, false);
             for &doc in docs {
                 postings_serializer.write_doc(doc, 1u32);
             }
@@ -120,7 +120,7 @@ impl SegmentPostings {
             IndexRecordOption::WithFreqs,
             fieldnorm_reader,
         );
-        postings_serializer.new_term(doc_and_tfs.len() as u32);
+        postings_serializer.new_term(doc_and_tfs.len() as u32, true);
         for &(doc, tf) in doc_and_tfs {
             postings_serializer.write_doc(doc, tf);
         }
@@ -238,14 +238,18 @@ impl Postings for SegmentPostings {
     }
 
     fn positions_with_offset(&mut self, offset: u32, output: &mut Vec<u32>) {
-        let term_freq = self.term_freq() as usize;
+        let term_freq = self.term_freq();
         if let Some(position_reader) = self.position_reader.as_mut() {
+            debug_assert!(
+                !self.block_cursor.freqs().is_empty(),
+                "No positions available"
+            );
             let read_offset = self.block_cursor.position_offset()
                 + (self.block_cursor.freqs()[..self.cur]
                     .iter()
                     .cloned()
                     .sum::<u32>() as u64);
-            output.resize(term_freq, 0u32);
+            output.resize(term_freq as usize, 0u32);
             position_reader.read(read_offset, &mut output[..]);
             let mut cum = offset;
             for output_mut in output.iter_mut() {

src/postings/serializer.rs

@@ -168,7 +168,12 @@ impl<'a> FieldSerializer<'a> {
     /// * term - the term. It needs to come after the previous term according to the lexicographical
     ///   order.
     /// * term_doc_freq - return the number of document containing the term.
-    pub fn new_term(&mut self, term: &[u8], term_doc_freq: u32) -> io::Result<()> {
+    pub fn new_term(
+        &mut self,
+        term: &[u8],
+        term_doc_freq: u32,
+        record_term_freq: bool,
+    ) -> io::Result<()> {
         assert!(
             !self.term_open,
             "Called new_term, while the previous term was not closed."
@@ -177,7 +182,8 @@ impl<'a> FieldSerializer<'a> {
         self.postings_serializer.clear();
         self.current_term_info = self.current_term_info();
         self.term_dictionary_builder.insert_key(term)?;
-        self.postings_serializer.new_term(term_doc_freq);
+        self.postings_serializer
+            .new_term(term_doc_freq, record_term_freq);
         Ok(())
     }
 
@@ -330,10 +336,10 @@ impl<W: Write> PostingsSerializer<W> {
         }
     }
 
-    pub fn new_term(&mut self, term_doc_freq: u32) {
+    pub fn new_term(&mut self, term_doc_freq: u32, record_term_freq: bool) {
         self.bm25_weight = None;
 
-        self.term_has_freq = self.mode.has_freq() && term_doc_freq != 0;
+        self.term_has_freq = self.mode.has_freq() && record_term_freq;
         if !self.term_has_freq {
             return;
         }
@@ -349,7 +355,7 @@ impl<W: Write> PostingsSerializer<W> {
             return;
         }
 
-        self.bm25_weight = Some(Bm25Weight::for_one_term(
+        self.bm25_weight = Some(Bm25Weight::for_one_term_without_explain(
             term_doc_freq as u64,
             num_docs_in_segment,
             self.avg_fieldnorm,

src/query/bm25.rs

@@ -77,7 +77,7 @@ pub struct Bm25Params {
 /// A struct used for computing BM25 scores.
 #[derive(Clone)]
 pub struct Bm25Weight {
-    idf_explain: Explanation,
+    idf_explain: Option<Explanation>,
     weight: Score,
     cache: [Score; 256],
     average_fieldnorm: Score,
@@ -147,11 +147,30 @@ impl Bm25Weight {
         idf_explain.add_const("N, total number of docs", total_num_docs as Score);
         Bm25Weight::new(idf_explain, avg_fieldnorm)
     }
+    /// Construct a [Bm25Weight] for a single term.
+    /// This method does not carry the [Explanation] for the idf.
+    pub fn for_one_term_without_explain(
+        term_doc_freq: u64,
+        total_num_docs: u64,
+        avg_fieldnorm: Score,
+    ) -> Bm25Weight {
+        let idf = idf(term_doc_freq, total_num_docs);
+        Bm25Weight::new_without_explain(idf, avg_fieldnorm)
+    }
 
     pub(crate) fn new(idf_explain: Explanation, average_fieldnorm: Score) -> Bm25Weight {
         let weight = idf_explain.value() * (1.0 + K1);
         Bm25Weight {
-            idf_explain,
+            idf_explain: Some(idf_explain),
+            weight,
+            cache: compute_tf_cache(average_fieldnorm),
+            average_fieldnorm,
+        }
+    }
+    pub(crate) fn new_without_explain(idf: f32, average_fieldnorm: Score) -> Bm25Weight {
+        let weight = idf * (1.0 + K1);
+        Bm25Weight {
+            idf_explain: None,
             weight,
             cache: compute_tf_cache(average_fieldnorm),
             average_fieldnorm,
@@ -202,7 +221,9 @@ impl Bm25Weight {
 
         let mut explanation = Explanation::new("TermQuery, product of...", score);
         explanation.add_detail(Explanation::new("(K1+1)", K1 + 1.0));
-        explanation.add_detail(self.idf_explain.clone());
+        if let Some(idf_explain) = &self.idf_explain {
+            explanation.add_detail(idf_explain.clone());
+        }
         explanation.add_detail(tf_explanation);
         explanation
     }

src/query/boost_query.rs

@@ -74,7 +74,8 @@ impl Weight for BoostWeight {
     fn explain(&self, reader: &SegmentReader, doc: u32) -> crate::Result<Explanation> {
         let underlying_explanation = self.weight.explain(reader, doc)?;
         let score = underlying_explanation.value() * self.boost;
-        let mut explanation = Explanation::new(format!("Boost x{} of ...", self.boost), score);
+        let mut explanation =
+            Explanation::new_with_string(format!("Boost x{} of ...", self.boost), score);
         explanation.add_detail(underlying_explanation);
         Ok(explanation)
     }
@@ -151,7 +152,7 @@ mod tests {
         let explanation = query.explain(&searcher, DocAddress::new(0, 0u32)).unwrap();
         assert_eq!(
             explanation.to_pretty_json(),
-            "{\n  \"value\": 0.2,\n  \"description\": \"Boost x0.2 of ...\",\n  \"details\": [\n    {\n      \"value\": 1.0,\n      \"description\": \"AllQuery\",\n      \"context\": []\n    }\n  ],\n  \"context\": []\n}"
+            "{\n  \"value\": 0.2,\n  \"description\": \"Boost x0.2 of ...\",\n  \"details\": [\n    {\n      \"value\": 1.0,\n      \"description\": \"AllQuery\"\n    }\n  ]\n}"
         );
         Ok(())
     }

src/query/const_score_query.rs

@@ -164,11 +164,9 @@ mod tests {
   "details": [
     {
       "value": 1.0,
-      "description": "AllQuery",
-      "context": []
+      "description": "AllQuery"
     }
-  ],
-  "context": []
+  ]
 }"#
         );
         Ok(())

src/query/explanation.rs

@@ -1,3 +1,4 @@
+use std::borrow::Cow;
 use std::fmt;
 
 use serde::Serialize;
@@ -16,12 +17,12 @@ pub(crate) fn does_not_match(doc: DocId) -> TantivyError {
 #[derive(Clone, Serialize)]
 pub struct Explanation {
     value: Score,
-    description: String,
-    #[serde(skip_serializing_if = "Vec::is_empty")]
-    details: Vec<Explanation>,
-    context: Vec<String>,
+    description: Cow<'static, str>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    details: Option<Vec<Explanation>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    context: Option<Vec<String>>,
 }
-
 impl fmt::Debug for Explanation {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "Explanation({})", self.to_pretty_json())
@@ -30,12 +31,21 @@ impl fmt::Debug for Explanation {
 
 impl Explanation {
     /// Creates a new explanation object.
-    pub fn new<T: ToString>(description: T, value: Score) -> Explanation {
+    pub fn new_with_string(description: String, value: Score) -> Explanation {
         Explanation {
             value,
-            description: description.to_string(),
-            details: vec![],
-            context: vec![],
+            description: Cow::Owned(description),
+            details: None,
+            context: None,
+        }
+    }
+    /// Creates a new explanation object.
+    pub fn new(description: &'static str, value: Score) -> Explanation {
+        Explanation {
+            value,
+            description: Cow::Borrowed(description),
+            details: None,
+            context: None,
         }
     }
 
@@ -48,17 +58,21 @@ impl Explanation {
     ///
     /// Details are treated as child of the current node.
     pub fn add_detail(&mut self, child_explanation: Explanation) {
-        self.details.push(child_explanation);
+        self.details
+            .get_or_insert_with(Vec::new)
+            .push(child_explanation);
     }
 
     /// Adds some extra context to the explanation.
     pub fn add_context(&mut self, context: String) {
-        self.context.push(context);
+        self.context.get_or_insert_with(Vec::new).push(context);
     }
 
     /// Shortcut for `self.details.push(Explanation::new(name, value));`
-    pub fn add_const<T: ToString>(&mut self, name: T, value: Score) {
-        self.details.push(Explanation::new(name, value));
+    pub fn add_const(&mut self, name: &'static str, value: Score) {
+        self.details
+            .get_or_insert_with(Vec::new)
+            .push(Explanation::new(name, value));
     }
 
     /// Returns an indented json representation of the explanation tree for debug usage.

src/query/term_query/term_query.rs

@@ -101,7 +101,7 @@ impl TermQuery {
                 ..
             } => Bm25Weight::for_terms(statistics_provider, &[self.term.clone()])?,
             EnableScoring::Disabled { .. } => {
-                Bm25Weight::new(Explanation::new("<no score>".to_string(), 1.0f32), 1.0f32)
+                Bm25Weight::new(Explanation::new("<no score>", 1.0f32), 1.0f32)
             }
         };
         let scoring_enabled = enable_scoring.is_scoring_enabled();

src/schema/bytes_options.rs

@@ -40,21 +40,25 @@ impl From<BytesOptionsDeser> for BytesOptions {
 
 impl BytesOptions {
     /// Returns true if the value is indexed.
+    #[inline]
     pub fn is_indexed(&self) -> bool {
         self.indexed
     }
 
     /// Returns true if and only if the value is normed.
+    #[inline]
     pub fn fieldnorms(&self) -> bool {
         self.fieldnorms
     }
 
     /// Returns true if the value is a fast field.
+    #[inline]
     pub fn is_fast(&self) -> bool {
         self.fast
     }
 
     /// Returns true if the value is stored.
+    #[inline]
     pub fn is_stored(&self) -> bool {
         self.stored
     }

src/schema/date_time_options.rs

@@ -27,21 +27,25 @@ pub struct DateOptions {
 
 impl DateOptions {
     /// Returns true iff the value is stored.
+    #[inline]
     pub fn is_stored(&self) -> bool {
         self.stored
     }
 
     /// Returns true iff the value is indexed and therefore searchable.
+    #[inline]
     pub fn is_indexed(&self) -> bool {
         self.indexed
     }
 
     /// Returns true iff the field has fieldnorm.
+    #[inline]
     pub fn fieldnorms(&self) -> bool {
         self.fieldnorms && self.indexed
     }
 
     /// Returns true iff the value is a fast field.
+    #[inline]
     pub fn is_fast(&self) -> bool {
         self.fast
     }

src/schema/facet.rs

@@ -131,16 +131,16 @@ impl Facet {
     pub fn from_path<Path>(path: Path) -> Facet
     where
         Path: IntoIterator,
-        Path::Item: ToString,
+        Path::Item: AsRef<str>,
     {
         let mut facet_string: String = String::with_capacity(100);
         let mut step_it = path.into_iter();
         if let Some(step) = step_it.next() {
-            facet_string.push_str(&step.to_string());
+            facet_string.push_str(step.as_ref());
         }
         for step in step_it {
             facet_string.push(FACET_SEP_CHAR);
-            facet_string.push_str(&step.to_string());
+            facet_string.push_str(step.as_ref());
         }
         Facet(facet_string)
     }

src/schema/facet_options.rs

@@ -14,6 +14,7 @@ pub struct FacetOptions {
 
 impl FacetOptions {
     /// Returns true if the value is stored.
+    #[inline]
     pub fn is_stored(&self) -> bool {
         self.stored
     }

src/schema/field_entry.rs

@@ -108,7 +108,16 @@ impl FieldEntry {
         self.field_type.is_fast()
     }
 
+    /// Returns true if the field has the expand dots option set (for json fields)
+    pub fn is_expand_dots_enabled(&self) -> bool {
+        match self.field_type {
+            FieldType::JsonObject(ref options) => options.is_expand_dots_enabled(),
+            _ => false,
+        }
+    }
+
     /// Returns true if the field is stored
+    #[inline]
     pub fn is_stored(&self) -> bool {
         match self.field_type {
             FieldType::U64(ref options)

src/schema/field_type.rs

@@ -3,6 +3,7 @@ use std::str::FromStr;
 
 use base64::engine::general_purpose::STANDARD as BASE64;
 use base64::Engine;
+use columnar::ColumnType;
 use serde::{Deserialize, Serialize};
 use serde_json::Value as JsonValue;
 use thiserror::Error;
@@ -47,7 +48,7 @@ pub enum ValueParsingError {
 ///
 /// Contrary to FieldType, this does
 /// not include the way the field must be indexed.
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
 #[repr(u8)]
 pub enum Type {
     /// `&str`
@@ -72,6 +73,21 @@ pub enum Type {
     IpAddr = b'p',
 }
 
+impl From<ColumnType> for Type {
+    fn from(value: ColumnType) -> Self {
+        match value {
+            ColumnType::Str => Type::Str,
+            ColumnType::U64 => Type::U64,
+            ColumnType::I64 => Type::I64,
+            ColumnType::F64 => Type::F64,
+            ColumnType::Bool => Type::Bool,
+            ColumnType::DateTime => Type::Date,
+            ColumnType::Bytes => Type::Bytes,
+            ColumnType::IpAddr => Type::IpAddr,
+        }
+    }
+}
+
 const ALL_TYPES: [Type; 10] = [
     Type::Str,
     Type::U64,

src/schema/ip_options.rs

@@ -31,21 +31,25 @@ pub struct IpAddrOptions {
 
 impl IpAddrOptions {
     /// Returns true iff the value is a fast field.
+    #[inline]
     pub fn is_fast(&self) -> bool {
         self.fast
     }
 
     /// Returns `true` if the ip address should be stored in the doc store.
+    #[inline]
     pub fn is_stored(&self) -> bool {
         self.stored
     }
 
     /// Returns true iff the value is indexed and therefore searchable.
+    #[inline]
     pub fn is_indexed(&self) -> bool {
         self.indexed
     }
 
     /// Returns true if and only if the value is normed.
+    #[inline]
     pub fn fieldnorms(&self) -> bool {
         self.fieldnorms
     }

src/schema/json_object_options.rs

@@ -46,17 +46,20 @@ pub struct JsonObjectOptions {
 
 impl JsonObjectOptions {
     /// Returns `true` if the json object should be stored.
+    #[inline]
     pub fn is_stored(&self) -> bool {
         self.stored
     }
 
     /// Returns `true` iff the json object should be indexed.
+    #[inline]
     pub fn is_indexed(&self) -> bool {
         self.indexing.is_some()
     }
 
     /// Returns true if and only if the json object fields are
     /// to be treated as fast fields.
+    #[inline]
     pub fn is_fast(&self) -> bool {
         matches!(self.fast, FastFieldTextOptions::IsEnabled(true))
             || matches!(
@@ -66,6 +69,7 @@ impl JsonObjectOptions {
     }
 
     /// Returns true if and only if the value is a fast field.
+    #[inline]
     pub fn get_fast_field_tokenizer_name(&self) -> Option<&str> {
         match &self.fast {
             FastFieldTextOptions::IsEnabled(true) | FastFieldTextOptions::IsEnabled(false) => None,
@@ -87,6 +91,7 @@ impl JsonObjectOptions {
     ///
     /// If disabled, the "." needs to be escaped:
     /// `k8s\.node\.id:5`.
+    #[inline]
     pub fn is_expand_dots_enabled(&self) -> bool {
         self.expand_dots_enabled
     }
@@ -103,6 +108,7 @@ impl JsonObjectOptions {
     /// If set to `Some` then both int and str values will be indexed.
     /// The inner `TextFieldIndexing` will however, only apply to the str values
     /// in the json object.
+    #[inline]
     pub fn get_text_indexing_options(&self) -> Option<&TextFieldIndexing> {
         self.indexing.as_ref()
     }

src/schema/numeric_options.rs

@@ -57,26 +57,31 @@ impl From<NumericOptionsDeser> for NumericOptions {
 
 impl NumericOptions {
     /// Returns true iff the value is stored in the doc store.
+    #[inline]
     pub fn is_stored(&self) -> bool {
         self.stored
     }
 
     /// Returns true iff the value is indexed and therefore searchable.
+    #[inline]
     pub fn is_indexed(&self) -> bool {
         self.indexed
     }
 
     /// Returns true iff the field has fieldnorm.
+    #[inline]
     pub fn fieldnorms(&self) -> bool {
         self.fieldnorms && self.indexed
     }
 
     /// Returns true iff the value is a fast field.
+    #[inline]
     pub fn is_fast(&self) -> bool {
         self.fast
     }
 
     /// Returns true if values should be coerced to numbers.
+    #[inline]
     pub fn should_coerce(&self) -> bool {
         self.coerce
     }

src/schema/schema.rs

@@ -8,6 +8,7 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 use super::ip_options::IpAddrOptions;
 use super::*;
+use crate::json_utils::split_json_path;
 use crate::schema::bytes_options::BytesOptions;
 use crate::TantivyError;
 
@@ -30,7 +31,7 @@ use crate::TantivyError;
 /// let body_field = schema_builder.add_text_field("body", TEXT);
 /// let schema = schema_builder.build();
 /// ```
-#[derive(Default)]
+#[derive(Debug, Default)]
 pub struct SchemaBuilder {
     fields: Vec<FieldEntry>,
     fields_map: HashMap<String, Field>,
@@ -328,12 +329,19 @@ impl Schema {
         if let Some(field) = self.0.fields_map.get(full_path) {
             return Some((*field, ""));
         }
+
         let mut splitting_period_pos: Vec<usize> = locate_splitting_dots(full_path);
         while let Some(pos) = splitting_period_pos.pop() {
             let (prefix, suffix) = full_path.split_at(pos);
+
             if let Some(field) = self.0.fields_map.get(prefix) {
                 return Some((*field, &suffix[1..]));
             }
+            // JSON path may contain a dot, for now we try both variants to find the field.
+            let prefix = split_json_path(prefix).join(".");
+            if let Some(field) = self.0.fields_map.get(&prefix) {
+                return Some((*field, &suffix[1..]));
+            }
         }
         None
     }
@@ -349,6 +357,7 @@ impl Schema {
     pub fn find_field_with_default<'a>(
         &self,
         full_path: &'a str,
+
         default_field_opt: Option<Field>,
     ) -> Option<(Field, &'a str)> {
         let (field, json_path) = self

src/schema/text_options.rs

@@ -72,16 +72,19 @@ fn is_false(val: &bool) -> bool {
 
 impl TextOptions {
     /// Returns the indexing options.
+    #[inline]
     pub fn get_indexing_options(&self) -> Option<&TextFieldIndexing> {
         self.indexing.as_ref()
     }
 
     /// Returns true if the text is to be stored.
+    #[inline]
     pub fn is_stored(&self) -> bool {
         self.stored
     }
 
     /// Returns true if and only if the value is a fast field.
+    #[inline]
     pub fn is_fast(&self) -> bool {
         matches!(self.fast, FastFieldTextOptions::IsEnabled(true))
             || matches!(
@@ -91,6 +94,7 @@ impl TextOptions {
     }
 
     /// Returns true if and only if the value is a fast field.
+    #[inline]
     pub fn get_fast_field_tokenizer_name(&self) -> Option<&str> {
         match &self.fast {
             FastFieldTextOptions::IsEnabled(true) | FastFieldTextOptions::IsEnabled(false) => None,
@@ -101,6 +105,7 @@ impl TextOptions {
     }
 
     /// Returns true if values should be coerced to strings (numbers, null).
+    #[inline]
     pub fn should_coerce(&self) -> bool {
         self.coerce
     }

src/space_usage/mod.rs

@@ -117,6 +117,7 @@ impl SegmentSpaceUsage {
         use self::ComponentSpaceUsage::*;
         use crate::SegmentComponent::*;
         match component {
+            FieldList => ComponentSpaceUsage::Basic(ByteCount::from(0u64)),
             Postings => PerField(self.postings().clone()),
             Positions => PerField(self.positions().clone()),
             FastFields => PerField(self.fast_fields().clone()),

sstable/Cargo.toml

@@ -11,16 +11,22 @@ description = "sstables for tantivy"
 
 [dependencies]
 common = {version= "0.6", path="../common", package="tantivy-common"}
-tantivy-fst = "0.4"
+tantivy-bitpacker = { version= "0.5", path="../bitpacker" }
+tantivy-fst = "0.5"
 # experimental gives us access to Decompressor::upper_bound
 zstd = { version = "0.13", features = ["experimental"] }
 
 [dev-dependencies]
 proptest = "1"
-criterion = "0.5"
+criterion = { version = "0.5", default-features = false }
 names = "0.14"
 rand = "0.8"
 
 [[bench]]
 name = "stream_bench"
 harness = false
+
+[[bench]]
+name = "ord_to_term"
+harness = false
+

sstable/README.md

@@ -89,39 +89,71 @@ Note: as the SSTable does not support redundant keys, there is no ambiguity betw
 
 ### SSTFooter
 ```
-+-------+-------+-----+------------------+------------+-------------+---------+---------+
-| Block | Block | ... | FirstLayerOffset | LayerCount | IndexOffset | NumTerm | Version |
-+-------+-------+-----+------------------+------------+-------------+---------+---------+
-|----(# of blocks)----|
++-----+----------------+-------------+-------------+---------+---------+
+| Fst | BlockAddrStore | StoreOffset | IndexOffset | NumTerm | Version |
++-----+----------------+-------------+-------------+---------+---------+
 ```
-- Block(SSTBlock): uses IndexValue for its Values format
-- FirstLayerOffset(u64): Offset between the start of the footer and the start of the top level index
-- LayerCount(u32): Number of layers of index (min 1) ## TODO do we want to use 0 as a marker for no layers? It makes small sstables 12 bytes more compact (the 0u32 would alias with the "end of sstable marker")
+- Fst(Fst): finite state transducer mapping keys to a block number
+- BlockAddrStore(BlockAddrStore): store mapping a block number to its BlockAddr
+- StoreOffset(u64): Offset to start of the BlockAddrStore. If zero, see the SingleBlockSStable section
 - IndexOffset(u64): Offset to the start of the SSTFooter
 - NumTerm(u64): number of terms in the sstable
 - Version(u32): Currently equal to 3
 
-Blocks referencing the main table and block referencing the index itself are encoded the same way and
-are not directly differentiated. Offsets in blocks referencing the index are relative to the start of
-the footer, blocks referencing the main table are relative to the start of that table.
+### Fst
 
-### IndexValue
-```
-+------------+----------+-------+-------+-----+
-| EntryCount | StartPos | Entry | Entry | ... |
-+------------+----------+-------+-------+-----+
-                        |---( # of entries)---|
-```
+Fst is in the format of tantivy\_fst
 
-- EntryCount(VInt): number of entries
-- StartPos(VInt): the start pos of the first (data) block referenced by this (index) block
-- Entry (IndexEntry)
+### BlockAddrStore
 
-### Entry
-```
-+----------+--------------+
-| BlockLen | FirstOrdinal |
-+----------+--------------+
-```
-- BlockLen(VInt): length of the block
-- FirstOrdinal(VInt): ordinal of the first element in the given block
++---------+-----------+-----------+-----+-----------+-----------+-----+
+| MetaLen | BlockMeta | BlockMeta | ... | BlockData | BlockData | ... |
++---------+-----------+-----------+-----+-----------+-----------+-----+
+          |---------(N blocks)----------|---------(N blocks)----------|
+
+- MetaLen(u64): length of the BlockMeta section
+- BlockMeta(BlockAddrBlockMetadata): metadata to seek through BlockData
+- BlockData(CompactedBlockAddr): bitpacked per block metadata
+
+### BlockAddrBlockMetadata
+
++--------+------------+--------------+------------+--------------+-------------------+-----------------+----------+
+| Offset | RangeStart | FirstOrdinal | RangeSlope | OrdinalSlope | FirstOrdinalNBits | RangeStartNBits | BlockLen |
++--------+------------+--------------+------------+--------------+-------------------+-----------------+----------+
+
+- Offset(u64): offset of the corresponding BlockData in the datastream
+- RangeStart(u64): the start position of the first block
+- FirstOrdinal(u64): the first ordinal of the first block
+- RangeSlope(u32): slope predicted for start range evolution (see computation in BlockData)
+- OrdinalSlope(u64): slope predicted for first ordinal evolution (see computation in BlockData)
+- FirstOrdinalNBits(u8): number of bits per ordinal in datastream (see computation in BlockData)
+- RangeStartNBits(u8): number of bits per range start in datastream (see computation in BlockData)
+
+### BlockData
+
++-----------------+-------------------+---------------+
+| RangeStartDelta | FirstOrdinalDelta | FinalRangeEnd |
++-----------------+-------------------+---------------+
+|------(BlockLen repetitions)---------|
+
+- RangeStartDelta(var): RangeStartNBits *bits* of little endian number. See below for decoding
+- FirstOrdinalDelta(var): FirstOrdinalNBits *bits* of little endian number. See below for decoding
+- FinalRangeEnd(var): RangeStartNBits *bits* of integer. See below for decoding
+
+converting a BlockData of index Index and a BlockAddrBlockMetadata to an actual block address is done as follow:
+range\_prediction := RangeStart + Index * RangeSlop;
+range\_derivation := RangeStartDelta - (1 << (RangeStartNBits-1));
+range\_start := range\_prediction + range\_derivation
+
+The same computation can be done for ordinal.
+
+Note that `range_derivation` can take negative value. `RangeStartDelta` is just its translation to a positive range.
+
+
+## SingleBlockSStable
+
+The format used for the index is meant to be compact, however it has a constant cost of around 70
+bytes, which isn't negligible for a table containing very few keys.
+To limit the impact of that constant cost, single block sstable omit the Fst and BlockAddrStore from
+their index. Instead a block with first ordinal of 0, range start of 0 and range end of IndexOffset
+is implicitly used for every operations.

sstable/benches/ord_to_term.rs

@@ -0,0 +1,110 @@
+use std::sync::Arc;
+
+use common::file_slice::FileSlice;
+use common::OwnedBytes;
+use criterion::{criterion_group, criterion_main, Criterion};
+use tantivy_sstable::{self, Dictionary, MonotonicU64SSTable};
+
+fn make_test_sstable(suffix: &str) -> FileSlice {
+    let mut builder = Dictionary::<MonotonicU64SSTable>::builder(Vec::new()).unwrap();
+
+    // 125 mio elements
+    for elem in 0..125_000_000 {
+        let key = format!("prefix.{elem:07X}{suffix}").into_bytes();
+        builder.insert(&key, &elem).unwrap();
+    }
+
+    let table = builder.finish().unwrap();
+    let table = Arc::new(OwnedBytes::new(table));
+    let slice = common::file_slice::FileSlice::new(table.clone());
+
+    slice
+}
+
+pub fn criterion_benchmark(c: &mut Criterion) {
+    {
+        let slice = make_test_sstable(".suffix");
+        let dict = Dictionary::<MonotonicU64SSTable>::open(slice.clone()).unwrap();
+        c.bench_function("ord_to_term_suffix", |b| {
+            let mut res = Vec::new();
+            b.iter(|| {
+                assert!(dict.ord_to_term(100_000, &mut res).unwrap());
+                assert!(dict.ord_to_term(19_000_000, &mut res).unwrap());
+            })
+        });
+        c.bench_function("open_and_ord_to_term_suffix", |b| {
+            let mut res = Vec::new();
+            b.iter(|| {
+                let dict = Dictionary::<MonotonicU64SSTable>::open(slice.clone()).unwrap();
+                assert!(dict.ord_to_term(100_000, &mut res).unwrap());
+                assert!(dict.ord_to_term(19_000_000, &mut res).unwrap());
+            })
+        });
+        c.bench_function("term_ord_suffix", |b| {
+            b.iter(|| {
+                assert_eq!(
+                    dict.term_ord(b"prefix.00186A0.suffix").unwrap().unwrap(),
+                    100_000
+                );
+                assert_eq!(
+                    dict.term_ord(b"prefix.121EAC0.suffix").unwrap().unwrap(),
+                    19_000_000
+                );
+            })
+        });
+        c.bench_function("open_and_term_ord_suffix", |b| {
+            b.iter(|| {
+                let dict = Dictionary::<MonotonicU64SSTable>::open(slice.clone()).unwrap();
+                assert_eq!(
+                    dict.term_ord(b"prefix.00186A0.suffix").unwrap().unwrap(),
+                    100_000
+                );
+                assert_eq!(
+                    dict.term_ord(b"prefix.121EAC0.suffix").unwrap().unwrap(),
+                    19_000_000
+                );
+            })
+        });
+    }
+    {
+        let slice = make_test_sstable("");
+        let dict = Dictionary::<MonotonicU64SSTable>::open(slice.clone()).unwrap();
+        c.bench_function("ord_to_term", |b| {
+            let mut res = Vec::new();
+            b.iter(|| {
+                assert!(dict.ord_to_term(100_000, &mut res).unwrap());
+                assert!(dict.ord_to_term(19_000_000, &mut res).unwrap());
+            })
+        });
+        c.bench_function("open_and_ord_to_term", |b| {
+            let mut res = Vec::new();
+            b.iter(|| {
+                let dict = Dictionary::<MonotonicU64SSTable>::open(slice.clone()).unwrap();
+                assert!(dict.ord_to_term(100_000, &mut res).unwrap());
+                assert!(dict.ord_to_term(19_000_000, &mut res).unwrap());
+            })
+        });
+        c.bench_function("term_ord", |b| {
+            b.iter(|| {
+                assert_eq!(dict.term_ord(b"prefix.00186A0").unwrap().unwrap(), 100_000);
+                assert_eq!(
+                    dict.term_ord(b"prefix.121EAC0").unwrap().unwrap(),
+                    19_000_000
+                );
+            })
+        });
+        c.bench_function("open_and_term_ord", |b| {
+            b.iter(|| {
+                let dict = Dictionary::<MonotonicU64SSTable>::open(slice.clone()).unwrap();
+                assert_eq!(dict.term_ord(b"prefix.00186A0").unwrap().unwrap(), 100_000);
+                assert_eq!(
+                    dict.term_ord(b"prefix.121EAC0").unwrap().unwrap(),
+                    19_000_000
+                );
+            })
+        });
+    }
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);

sstable/src/delta.rs

@@ -20,7 +20,6 @@ where W: io::Write
     // Only here to avoid allocations.
     stateless_buffer: Vec<u8>,
     block_len: usize,
-    compress: bool,
 }
 
 impl<W, TValueWriter> DeltaWriter<W, TValueWriter>
@@ -35,18 +34,6 @@ where
             value_writer: TValueWriter::default(),
             stateless_buffer: Vec::new(),
             block_len: BLOCK_LEN,
-            compress: true,
-        }
-    }
-
-    pub fn new_no_compression(wrt: W) -> Self {
-        DeltaWriter {
-            block: Vec::with_capacity(BLOCK_LEN * 2),
-            write: CountingWriter::wrap(BufWriter::new(wrt)),
-            value_writer: TValueWriter::default(),
-            stateless_buffer: Vec::new(),
-            block_len: BLOCK_LEN,
-            compress: false,
         }
     }
 
@@ -66,7 +53,7 @@ where
 
         let block_len = buffer.len() + self.block.len();
 
-        if block_len > 2048 && self.compress {
+        if block_len > 2048 {
             buffer.extend_from_slice(&self.block);
             self.block.clear();
 

sstable/src/dictionary.rs

@@ -9,8 +9,11 @@ use common::{BinarySerializable, OwnedBytes};
 use tantivy_fst::automaton::AlwaysMatch;
 use tantivy_fst::Automaton;
 
+use crate::sstable_index_v3::SSTableIndexV3Empty;
 use crate::streamer::{Streamer, StreamerBuilder};
-use crate::{BlockAddr, DeltaReader, Reader, SSTable, SSTableIndex, TermOrdinal, VoidSSTable};
+use crate::{
+    BlockAddr, DeltaReader, Reader, SSTable, SSTableIndex, SSTableIndexV3, TermOrdinal, VoidSSTable,
+};
 
 /// An SSTable is a sorted map that associates sorted `&[u8]` keys
 /// to any kind of typed values.
@@ -128,144 +131,99 @@ impl<TSSTable: SSTable> Dictionary<TSSTable> {
         key_range: impl RangeBounds<[u8]>,
         limit: Option<u64>,
     ) -> FileSlice {
-        // we don't perform great when limit is set to a large value, and sometime we use u64::MAX
-        // as a marker for no limit, so we'd better capture that.
-        // (not great means we decode up to the whole bottom layer index, which can take dozens of
-        // ms on a 100m term dictionary)
-        let limit = limit.filter(|limit| *limit != u64::MAX);
-
-        // TODO replace unwraps with proper error handling
-        let start_key = match key_range.start_bound() {
-            Bound::Included(key) | Bound::Excluded(key) => key,
-            Bound::Unbounded => &[],
-        };
-        let end_key = match key_range.end_bound() {
-            Bound::Included(key) | Bound::Excluded(key) => Some(key),
+        let first_block_id = match key_range.start_bound() {
+            Bound::Included(key) | Bound::Excluded(key) => {
+                let Some(first_block_id) = self.sstable_index.locate_with_key(key) else {
+                    return FileSlice::empty();
+                };
+                Some(first_block_id)
+            }
             Bound::Unbounded => None,
         };
-        let bounds = if let Some(limit) = limit {
-            let mut sstable_iterator = self.sstable_index.iterate_from_key(start_key).unwrap();
-            let Some(start_block) = sstable_iterator.value() else {
-                // range_start is after end of table
-                return FileSlice::empty();
-            };
-            if let Some(end_key) = end_key {
-                if sstable_iterator.key().unwrap() >= end_key {
-                    // the start and end keys are in the same block, return just that block
-                    return self.sstable_slice.slice(start_block.byte_range.clone());
-                }
-            }
-            let start_bound = start_block.byte_range.start;
 
-            sstable_iterator.advance().unwrap();
-            let Some(second_block) = sstable_iterator.value() else {
-                // we reached the end of the sstable, return everything from start_bound
-                return self.sstable_slice.slice(start_bound..);
-            };
-            let mut end_bound = second_block.byte_range.end;
-            if let Some(end_key) = end_key {
-                if sstable_iterator.key().unwrap() >= end_key {
-                    return self.sstable_slice.slice(start_bound..end_bound);
-                }
-            }
-
-            let target_ord = second_block.first_ordinal + limit;
-
-            while sstable_iterator.advance().unwrap() {
-                let block = sstable_iterator.value().unwrap();
-                if block.first_ordinal >= target_ord {
-                    break;
-                }
-                end_bound = block.byte_range.end;
-                if let Some(end_key) = end_key {
-                    if sstable_iterator.key().unwrap() >= end_key {
-                        break;
-                    }
-                }
-            }
-
-            let start_bound = Bound::Included(start_bound);
-            let end_bound = Bound::Excluded(end_bound);
-
-            (start_bound, end_bound)
-        } else {
-            let Some(start_block) = self.sstable_index.get_block_with_key(start_key).unwrap()
-            else {
-                // range_start is after end of table
-                return FileSlice::empty();
-            };
-            let start_bound = Bound::Included(start_block.byte_range.start);
-            let end_bound = if let Some(end_key) = end_key {
-                if let Some(end_block) = self.sstable_index.get_block_with_key(end_key).unwrap() {
-                    Bound::Excluded(end_block.byte_range.end)
-                } else {
-                    Bound::Unbounded
-                }
-            } else {
-                Bound::Unbounded
-            };
-            (start_bound, end_bound)
+        let last_block_id = match key_range.end_bound() {
+            Bound::Included(key) | Bound::Excluded(key) => self.sstable_index.locate_with_key(key),
+            Bound::Unbounded => None,
         };
 
-        self.sstable_slice.slice(bounds)
+        let start_bound = if let Some(first_block_id) = first_block_id {
+            let Some(block_addr) = self.sstable_index.get_block(first_block_id) else {
+                return FileSlice::empty();
+            };
+            Bound::Included(block_addr.byte_range.start)
+        } else {
+            Bound::Unbounded
+        };
+
+        let last_block_id = if let Some(limit) = limit {
+            let second_block_id = first_block_id.map(|id| id + 1).unwrap_or(0);
+            if let Some(block_addr) = self.sstable_index.get_block(second_block_id) {
+                let ordinal_limit = block_addr.first_ordinal + limit;
+                let last_block_limit = self.sstable_index.locate_with_ord(ordinal_limit);
+                if let Some(last_block_id) = last_block_id {
+                    Some(last_block_id.min(last_block_limit))
+                } else {
+                    Some(last_block_limit)
+                }
+            } else {
+                last_block_id
+            }
+        } else {
+            last_block_id
+        };
+        let end_bound = last_block_id
+            .and_then(|block_id| self.sstable_index.get_block(block_id))
+            .map(|block_addr| Bound::Excluded(block_addr.byte_range.end))
+            .unwrap_or(Bound::Unbounded);
+
+        self.sstable_slice.slice((start_bound, end_bound))
     }
 
     /// Opens a `TermDictionary`.
     pub fn open(term_dictionary_file: FileSlice) -> io::Result<Self> {
         let (main_slice, footer_len_slice) = term_dictionary_file.split_from_end(20);
         let mut footer_len_bytes: OwnedBytes = footer_len_slice.read_bytes()?;
-
-        // let layer_count = u32::deserialize(&mut footer_len_bytes)?;
         let index_offset = u64::deserialize(&mut footer_len_bytes)?;
         let num_terms = u64::deserialize(&mut footer_len_bytes)?;
         let version = u32::deserialize(&mut footer_len_bytes)?;
         let (sstable_slice, index_slice) = main_slice.split(index_offset as usize);
-        match version {
-            2 => {
-                // previous format, kept for backward compatibility
-                let sstable_index_bytes = index_slice.read_bytes()?;
-                // on the old format, the 1st layer necessarily start immediately, and there is
-                // only a single layer
-                let sstable_index =
-                    SSTableIndex::load(sstable_index_bytes, 1, 0).map_err(|_| {
-                        io::Error::new(io::ErrorKind::InvalidData, "SSTable corruption")
-                    })?;
-                Ok(Dictionary {
-                    sstable_slice,
-                    sstable_index,
-                    num_terms,
-                    phantom_data: PhantomData,
-                })
-            }
-            3 => {
-                let sstable_index_bytes = index_slice.read_bytes()?;
-                let (sstable_index_bytes, mut v3_footer_bytes) = sstable_index_bytes.rsplit(12);
-                let first_layer_offset = v3_footer_bytes.read_u64();
-                let layer_count = v3_footer_bytes.read_u32();
+        let sstable_index_bytes = index_slice.read_bytes()?;
 
-                let sstable_index = SSTableIndex::load(
-                    sstable_index_bytes,
-                    layer_count,
-                    first_layer_offset as usize,
-                )
-                .map_err(|_| io::Error::new(io::ErrorKind::InvalidData, "SSTable corruption"))?;
-                Ok(Dictionary {
-                    sstable_slice,
-                    sstable_index,
-                    num_terms,
-                    phantom_data: PhantomData,
-                })
+        let sstable_index = match version {
+            2 => SSTableIndex::V2(
+                crate::sstable_index_v2::SSTableIndex::load(sstable_index_bytes).map_err(|_| {
+                    io::Error::new(io::ErrorKind::InvalidData, "SSTable corruption")
+                })?,
+            ),
+            3 => {
+                let (sstable_index_bytes, mut footerv3_len_bytes) = sstable_index_bytes.rsplit(8);
+                let store_offset = u64::deserialize(&mut footerv3_len_bytes)?;
+                if store_offset != 0 {
+                    SSTableIndex::V3(
+                        SSTableIndexV3::load(sstable_index_bytes, store_offset).map_err(|_| {
+                            io::Error::new(io::ErrorKind::InvalidData, "SSTable corruption")
+                        })?,
+                    )
+                } else {
+                    // if store_offset is zero, there is no index, so we build a pseudo-index
+                    // assuming a single block of sstable covering everything.
+                    SSTableIndex::V3Empty(SSTableIndexV3Empty::load(index_offset as usize))
+                }
             }
             _ => {
                 return Err(io::Error::new(
                     io::ErrorKind::Other,
-                    format!(
-                        "Unsuported sstable version, expected {}, found {version}",
-                        crate::SSTABLE_VERSION,
-                    ),
+                    format!("Unsuported sstable version, expected one of [2, 3], found {version}"),
                 ))
             }
-        }
+        };
+
+        Ok(Dictionary {
+            sstable_slice,
+            sstable_index,
+            num_terms,
+            phantom_data: PhantomData,
+        })
     }
 
     /// Creates a term dictionary from the supplied bytes.
@@ -289,17 +247,68 @@ impl<TSSTable: SSTable> Dictionary<TSSTable> {
         self.num_terms as usize
     }
 
+    /// Decode a DeltaReader up to key, returning the number of terms traversed
+    ///
+    /// If the key was not found, returns Ok(None).
+    /// After calling this function, it is possible to call `DeltaReader::value` to get the
+    /// associated value.
+    fn decode_up_to_key<K: AsRef<[u8]>>(
+        &self,
+        key: K,
+        sstable_delta_reader: &mut DeltaReader<TSSTable::ValueReader>,
+    ) -> io::Result<Option<TermOrdinal>> {
+        let mut term_ord = 0;
+        let key_bytes = key.as_ref();
+        let mut ok_bytes = 0;
+        while sstable_delta_reader.advance()? {
+            let prefix_len = sstable_delta_reader.common_prefix_len();
+            let suffix = sstable_delta_reader.suffix();
+
+            match prefix_len.cmp(&ok_bytes) {
+                Ordering::Less => return Ok(None), // popped bytes already matched => too far
+                Ordering::Equal => (),
+                Ordering::Greater => {
+                    // the ok prefix is less than current entry prefix => continue to next elem
+                    term_ord += 1;
+                    continue;
+                }
+            }
+
+            // we have ok_bytes byte of common prefix, check if this key adds more
+            for (key_byte, suffix_byte) in key_bytes[ok_bytes..].iter().zip(suffix) {
+                match suffix_byte.cmp(key_byte) {
+                    Ordering::Less => break,              // byte too small
+                    Ordering::Equal => ok_bytes += 1,     // new matching byte
+                    Ordering::Greater => return Ok(None), // too far
+                }
+            }
+
+            if ok_bytes == key_bytes.len() {
+                if prefix_len + suffix.len() == ok_bytes {
+                    return Ok(Some(term_ord));
+                } else {
+                    // current key is a prefix of current element, not a match
+                    return Ok(None);
+                }
+            }
+
+            term_ord += 1;
+        }
+
+        Ok(None)
+    }
+
     /// Returns the ordinal associated with a given term.
     pub fn term_ord<K: AsRef<[u8]>>(&self, key: K) -> io::Result<Option<TermOrdinal>> {
         let key_bytes = key.as_ref();
 
-        let Some(block_addr) = self.sstable_index.get_block_with_key(key_bytes)? else {
+        let Some(block_addr) = self.sstable_index.get_block_with_key(key_bytes) else {
             return Ok(None);
         };
 
         let first_ordinal = block_addr.first_ordinal;
         let mut sstable_delta_reader = self.sstable_delta_reader_block(block_addr)?;
-        decode_up_to_key(key_bytes, &mut sstable_delta_reader)
+        self.decode_up_to_key(key_bytes, &mut sstable_delta_reader)
             .map(|opt| opt.map(|ord| ord + first_ordinal))
     }
 
@@ -314,7 +323,7 @@ impl<TSSTable: SSTable> Dictionary<TSSTable> {
     /// the buffer may be modified.
     pub fn ord_to_term(&self, ord: TermOrdinal, bytes: &mut Vec<u8>) -> io::Result<bool> {
         // find block in which the term would be
-        let block_addr = self.sstable_index.get_block_with_ord(ord)?;
+        let block_addr = self.sstable_index.get_block_with_ord(ord);
         let first_ordinal = block_addr.first_ordinal;
 
         // then search inside that block only
@@ -332,7 +341,7 @@ impl<TSSTable: SSTable> Dictionary<TSSTable> {
     /// Returns the number of terms in the dictionary.
     pub fn term_info_from_ord(&self, term_ord: TermOrdinal) -> io::Result<Option<TSSTable::Value>> {
         // find block in which the term would be
-        let block_addr = self.sstable_index.get_block_with_ord(term_ord)?;
+        let block_addr = self.sstable_index.get_block_with_ord(term_ord);
         let first_ordinal = block_addr.first_ordinal;
 
         // then search inside that block only
@@ -347,7 +356,7 @@ impl<TSSTable: SSTable> Dictionary<TSSTable> {
 
     /// Lookups the value corresponding to the key.
     pub fn get<K: AsRef<[u8]>>(&self, key: K) -> io::Result<Option<TSSTable::Value>> {
-        if let Some(block_addr) = self.sstable_index.get_block_with_key(key.as_ref())? {
+        if let Some(block_addr) = self.sstable_index.get_block_with_key(key.as_ref()) {
             let sstable_reader = self.sstable_delta_reader_block(block_addr)?;
             return self.do_get(key, sstable_reader);
         }
@@ -356,7 +365,7 @@ impl<TSSTable: SSTable> Dictionary<TSSTable> {
 
     /// Lookups the value corresponding to the key.
     pub async fn get_async<K: AsRef<[u8]>>(&self, key: K) -> io::Result<Option<TSSTable::Value>> {
-        if let Some(block_addr) = self.sstable_index.get_block_with_key(key.as_ref())? {
+        if let Some(block_addr) = self.sstable_index.get_block_with_key(key.as_ref()) {
             let sstable_reader = self.sstable_delta_reader_block_async(block_addr).await?;
             return self.do_get(key, sstable_reader);
         }
@@ -368,7 +377,7 @@ impl<TSSTable: SSTable> Dictionary<TSSTable> {
         key: K,
         mut reader: DeltaReader<TSSTable::ValueReader>,
     ) -> io::Result<Option<TSSTable::Value>> {
-        if let Some(_ord) = decode_up_to_key(key, &mut reader)? {
+        if let Some(_ord) = self.decode_up_to_key(key, &mut reader)? {
             Ok(Some(reader.value().clone()))
         } else {
             Ok(None)
@@ -405,56 +414,6 @@ impl<TSSTable: SSTable> Dictionary<TSSTable> {
     }
 }
 
-/// Decode a DeltaReader up to key, returning the number of terms traversed
-///
-/// If the key was not found, returns Ok(None).
-/// After calling this function, it is possible to call `DeltaReader::value` to get the
-/// associated value.
-pub(crate) fn decode_up_to_key<K: AsRef<[u8]>, TValueReader: crate::ValueReader>(
-    key: K,
-    sstable_delta_reader: &mut DeltaReader<TValueReader>,
-) -> io::Result<Option<TermOrdinal>> {
-    let mut term_ord = 0;
-    let key_bytes = key.as_ref();
-    let mut ok_bytes = 0;
-    while sstable_delta_reader.advance()? {
-        let prefix_len = sstable_delta_reader.common_prefix_len();
-        let suffix = sstable_delta_reader.suffix();
-
-        match prefix_len.cmp(&ok_bytes) {
-            Ordering::Less => return Ok(None), // popped bytes already matched => too far
-            Ordering::Equal => (),
-            Ordering::Greater => {
-                // the ok prefix is less than current entry prefix => continue to next elem
-                term_ord += 1;
-                continue;
-            }
-        }
-
-        // we have ok_bytes byte of common prefix, check if this key adds more
-        for (key_byte, suffix_byte) in key_bytes[ok_bytes..].iter().zip(suffix) {
-            match suffix_byte.cmp(key_byte) {
-                Ordering::Less => break,              // byte too small
-                Ordering::Equal => ok_bytes += 1,     // new matching byte
-                Ordering::Greater => return Ok(None), // too far
-            }
-        }
-
-        if ok_bytes == key_bytes.len() {
-            if prefix_len + suffix.len() == ok_bytes {
-                return Ok(Some(term_ord));
-            } else {
-                // current key is a prefix of current element, not a match
-                return Ok(None);
-            }
-        }
-
-        term_ord += 1;
-    }
-
-    Ok(None)
-}
-
 #[cfg(test)]
 mod tests {
     use std::ops::Range;
@@ -520,6 +479,8 @@ mod tests {
 
         let dictionary = Dictionary::<MonotonicU64SSTable>::open(slice).unwrap();
 
+        // if the last block is id 0, tests are meaningless
+        assert_ne!(dictionary.sstable_index.locate_with_ord(u64::MAX), 0);
         assert_eq!(dictionary.num_terms(), 0x3ffff);
         (dictionary, table)
     }
@@ -528,7 +489,7 @@ mod tests {
     fn test_ord_term_conversion() {
         let (dic, slice) = make_test_sstable();
 
-        let block = dic.sstable_index.get_block_with_ord(100_000).unwrap();
+        let block = dic.sstable_index.get_block_with_ord(100_000);
         slice.restrict(block.byte_range);
 
         let mut res = Vec::new();
@@ -554,11 +515,7 @@ mod tests {
 
         // end of a block
         let ordinal = block.first_ordinal - 1;
-        let new_range = dic
-            .sstable_index
-            .get_block_with_ord(ordinal)
-            .unwrap()
-            .byte_range;
+        let new_range = dic.sstable_index.get_block_with_ord(ordinal).byte_range;
         slice.restrict(new_range);
         assert!(dic.ord_to_term(ordinal, &mut res).unwrap());
         assert_eq!(res, format!("{ordinal:05X}").into_bytes());
@@ -568,7 +525,7 @@ mod tests {
 
         // before first block
         // 1st block must be loaded for key-related operations
-        let block = dic.sstable_index.get_block_with_ord(0).unwrap();
+        let block = dic.sstable_index.get_block_with_ord(0);
         slice.restrict(block.byte_range);
 
         assert!(dic.get(b"$$$").unwrap().is_none());
@@ -577,11 +534,7 @@ mod tests {
         // after last block
         // last block must be loaded for ord related operations
         let ordinal = 0x40000 + 10;
-        let new_range = dic
-            .sstable_index
-            .get_block_with_ord(ordinal)
-            .unwrap()
-            .byte_range;
+        let new_range = dic.sstable_index.get_block_with_ord(ordinal).byte_range;
         slice.restrict(new_range);
         assert!(!dic.ord_to_term(ordinal, &mut res).unwrap());
         assert!(dic.term_info_from_ord(ordinal).unwrap().is_none());
@@ -606,13 +559,11 @@ mod tests {
             .sstable_index
             .get_block_with_key(b"10000")
             .unwrap()
-            .unwrap()
             .byte_range;
         let end = dic
             .sstable_index
             .get_block_with_key(b"18000")
             .unwrap()
-            .unwrap()
             .byte_range;
         slice.restrict(start.start..end.end);
 

sstable/src/lib.rs

@@ -1,6 +1,6 @@
 use std::io::{self, Write};
-use std::num::NonZeroU64;
 use std::ops::Range;
+use std::usize;
 
 use merge::ValueMerger;
 
@@ -10,8 +10,9 @@ pub mod merge;
 mod streamer;
 pub mod value;
 
-mod sstable_index;
-pub use sstable_index::{BlockAddr, SSTableIndex, SSTableIndexBuilder};
+mod sstable_index_v3;
+pub use sstable_index_v3::{BlockAddr, SSTableIndex, SSTableIndexBuilder, SSTableIndexV3};
+mod sstable_index_v2;
 pub(crate) mod vint;
 pub use dictionary::Dictionary;
 pub use streamer::{Streamer, StreamerBuilder};
@@ -30,12 +31,6 @@ pub type TermOrdinal = u64;
 const DEFAULT_KEY_CAPACITY: usize = 50;
 const SSTABLE_VERSION: u32 = 3;
 
-// TODO tune that value. Maybe it's too little?
-#[cfg(not(test))]
-const DEFAULT_MAX_ROOT_BLOCKS: NonZeroU64 = unsafe { NonZeroU64::new_unchecked(32) };
-#[cfg(test)]
-const DEFAULT_MAX_ROOT_BLOCKS: NonZeroU64 = unsafe { NonZeroU64::new_unchecked(1) };
-
 /// Given two byte string returns the length of
 /// the longest common prefix.
 fn common_prefix_len(left: &[u8], right: &[u8]) -> usize {
@@ -61,7 +56,7 @@ pub trait SSTable: Sized {
     }
 
     fn writer<W: io::Write>(wrt: W) -> Writer<W, Self::ValueWriter> {
-        Writer::new(wrt, DEFAULT_MAX_ROOT_BLOCKS)
+        Writer::new(wrt)
     }
 
     fn delta_reader(reader: OwnedBytes) -> DeltaReader<Self::ValueReader> {
@@ -184,7 +179,6 @@ where W: io::Write
     delta_writer: DeltaWriter<W, TValueWriter>,
     num_terms: u64,
     first_ordinal_of_the_block: u64,
-    index_max_root_blocks: NonZeroU64,
 }
 
 impl<W, TValueWriter> Writer<W, TValueWriter>
@@ -197,18 +191,17 @@ where
     /// TODO remove this function. (See Issue #1727)
     #[doc(hidden)]
     pub fn create(wrt: W) -> io::Result<Self> {
-        Ok(Self::new(wrt, DEFAULT_MAX_ROOT_BLOCKS))
+        Ok(Self::new(wrt))
     }
 
     /// Creates a new `TermDictionaryBuilder`.
-    pub fn new(wrt: W, index_max_root_blocks: NonZeroU64) -> Self {
+    pub fn new(wrt: W) -> Self {
         Writer {
             previous_key: Vec::with_capacity(DEFAULT_KEY_CAPACITY),
             num_terms: 0u64,
             index_builder: SSTableIndexBuilder::default(),
             delta_writer: DeltaWriter::new(wrt),
             first_ordinal_of_the_block: 0u64,
-            index_max_root_blocks,
         }
     }
 
@@ -310,15 +303,11 @@ where
         // add a final empty block as an end marker
         wrt.write_all(&0u32.to_le_bytes())?;
 
-        let index_offset = wrt.written_bytes();
+        let offset = wrt.written_bytes();
 
-        let (layer_count, layer_offset): (u32, u64) = self
-            .index_builder
-            .serialize(&mut wrt, self.index_max_root_blocks)?;
-        wrt.write_all(&layer_offset.to_le_bytes())?;
-        wrt.write_all(&layer_count.to_le_bytes())?;
-
-        wrt.write_all(&index_offset.to_le_bytes())?;
+        let fst_len: u64 = self.index_builder.serialize(&mut wrt)?;
+        wrt.write_all(&fst_len.to_le_bytes())?;
+        wrt.write_all(&offset.to_le_bytes())?;
         wrt.write_all(&self.num_terms.to_le_bytes())?;
 
         SSTABLE_VERSION.serialize(&mut wrt)?;
@@ -398,12 +387,7 @@ mod test {
                 16, 17, 33, 18, 19, 17, 20, // data block
                 0, 0, 0, 0, // no more block
                 // index
-                8, 0, 0, 0, // size of index block
-                0, // compression
-                1, 0, 12, 0, 32, 17, 20, // index block
-                0, 0, 0, 0, // no more index block
-                0, 0, 0, 0, 0, 0, 0, 0, // first layer offset
-                1, 0, 0, 0, // layer count
+                0, 0, 0, 0, 0, 0, 0, 0, // fst lenght
                 16, 0, 0, 0, 0, 0, 0, 0, // index start offset
                 3, 0, 0, 0, 0, 0, 0, 0, // num term
                 3, 0, 0, 0, // version

sstable/src/sstable_index.rs

@@ -1,487 +0,0 @@
-use std::io::{self, Write};
-use std::ops::Range;
-
-use common::OwnedBytes;
-
-use crate::{common_prefix_len, SSTable, SSTableDataCorruption, TermOrdinal};
-
-#[derive(Debug, Clone)]
-pub struct SSTableIndex {
-    root_blocks: Vec<BlockMeta>,
-    layer_count: u32,
-    index_bytes: OwnedBytes,
-}
-
-impl Default for SSTableIndex {
-    fn default() -> Self {
-        SSTableIndex {
-            root_blocks: Vec::new(),
-            layer_count: 1,
-            index_bytes: OwnedBytes::empty(),
-        }
-    }
-}
-
-impl SSTableIndex {
-    /// Load an index from its binary representation
-    pub fn load(
-        data: OwnedBytes,
-        layer_count: u32,
-        first_layer_offset: usize,
-    ) -> Result<SSTableIndex, SSTableDataCorruption> {
-        let (index_bytes, first_layer_slice) = data.split(first_layer_offset);
-        let mut reader = IndexSSTable::reader(first_layer_slice);
-        let mut root_blocks = Vec::new();
-
-        while reader.advance().map_err(|_| SSTableDataCorruption)? {
-            root_blocks.push(BlockMeta {
-                last_key_or_greater: reader.key().to_vec(),
-                block_addr: reader.value().clone(),
-            });
-        }
-
-        Ok(SSTableIndex {
-            root_blocks,
-            layer_count,
-            index_bytes,
-            // index_bytes: OwnedBytes::empty(),
-        })
-    }
-
-    /// Get the [`BlockAddr`] of the block that would contain `key`.
-    ///
-    /// Returns None if `key` is lexicographically after the last key recorded.
-    pub fn get_block_with_key(&self, key: &[u8]) -> io::Result<Option<BlockAddr>> {
-        self.iterate_from_key(key).map(|iter| iter.value().cloned())
-    }
-
-    /// Get the [`BlockAddr`] of the block containing the `ord`-th term.
-    pub fn get_block_with_ord(&self, ord: TermOrdinal) -> io::Result<BlockAddr> {
-        let pos = self
-            .root_blocks
-            .binary_search_by_key(&ord, |block| block.block_addr.first_ordinal);
-
-        let root_pos = match pos {
-            Ok(pos) => pos,
-            // Err(0) can't happen as the sstable starts with ordinal zero
-            Err(pos) => pos - 1,
-        };
-
-        if self.layer_count == 1 {
-            return Ok(self.root_blocks[root_pos].block_addr.clone());
-        }
-
-        let mut next_layer_block_addr = self.root_blocks[root_pos].block_addr.clone();
-        for _ in 1..self.layer_count {
-            let mut sstable_delta_reader = IndexSSTable::delta_reader(
-                self.index_bytes
-                    .slice(next_layer_block_addr.byte_range.clone()),
-            );
-            while sstable_delta_reader.advance()? {
-                if sstable_delta_reader.value().first_ordinal > ord {
-                    break;
-                }
-                next_layer_block_addr = sstable_delta_reader.value().clone();
-            }
-        }
-        Ok(next_layer_block_addr)
-    }
-
-    pub(crate) fn iterate_from_key(&self, key: &[u8]) -> io::Result<ReaderOrSlice<'_>> {
-        let root_pos = self
-            .root_blocks
-            .binary_search_by_key(&key, |block| &block.last_key_or_greater);
-        let root_pos = match root_pos {
-            Ok(pos) => pos,
-            Err(pos) => {
-                if pos < self.root_blocks.len() {
-                    pos
-                } else {
-                    // after end of last block: no block matches
-                    return Ok(ReaderOrSlice::End);
-                }
-            }
-        };
-
-        let mut next_layer_block_addr = self.root_blocks[root_pos].block_addr.clone();
-        let mut last_delta_reader = None;
-        for _ in 1..self.layer_count {
-            // we don't enter this loop for 1 layer index
-            let mut sstable_delta_reader = IndexSSTable::delta_reader(
-                self.index_bytes.slice(next_layer_block_addr.byte_range),
-            );
-            crate::dictionary::decode_up_to_key(key, &mut sstable_delta_reader)?;
-            next_layer_block_addr = sstable_delta_reader.value().clone();
-            last_delta_reader = Some(sstable_delta_reader);
-        }
-
-        if let Some(delta_reader) = last_delta_reader {
-            // reconstruct the current key. We stopped either on the exact key, or just after
-            // either way, common_prefix_len is something that did not change between the
-            // last-key-before-target and the current pos, so those bytes must match the prefix of
-            // `key`. The next bytes can be obtained from the delta reader
-            let mut result_key = Vec::with_capacity(crate::DEFAULT_KEY_CAPACITY);
-            let common_prefix_len = delta_reader.common_prefix_len();
-            let suffix = delta_reader.suffix();
-            let new_len = delta_reader.common_prefix_len() + suffix.len();
-            result_key.resize(new_len, 0u8);
-            result_key[..common_prefix_len].copy_from_slice(&key[..common_prefix_len]);
-            result_key[common_prefix_len..].copy_from_slice(suffix);
-
-            let reader = crate::Reader {
-                key: result_key,
-                delta_reader,
-            };
-            Ok(ReaderOrSlice::Reader(reader))
-        } else {
-            // self.layer_count == 1, there is no lvl2 sstable to decode.
-            Ok(ReaderOrSlice::Iter(&self.root_blocks, root_pos))
-        }
-    }
-}
-
-pub(crate) enum ReaderOrSlice<'a> {
-    Reader(crate::Reader<crate::value::index::IndexValueReader>),
-    Iter(&'a [BlockMeta], usize),
-    End,
-}
-
-impl<'a> ReaderOrSlice<'a> {
-    pub fn advance(&mut self) -> Result<bool, SSTableDataCorruption> {
-        match self {
-            ReaderOrSlice::Reader(reader) => {
-                let res = reader.advance().map_err(|_| SSTableDataCorruption);
-                if !matches!(res, Ok(true)) {
-                    *self = ReaderOrSlice::End;
-                }
-                res
-            }
-            ReaderOrSlice::Iter(slice, index) => {
-                *index += 1;
-                if *index < slice.len() {
-                    Ok(true)
-                } else {
-                    *self = ReaderOrSlice::End;
-                    Ok(false)
-                }
-            }
-            ReaderOrSlice::End => Ok(false),
-        }
-    }
-
-    /// Get current key. Always Some(_) unless last call to advance returned something else than
-    /// Ok(true)
-    pub fn key(&self) -> Option<&[u8]> {
-        match self {
-            ReaderOrSlice::Reader(reader) => Some(reader.key()),
-            ReaderOrSlice::Iter(slice, index) => Some(&slice[*index].last_key_or_greater),
-            ReaderOrSlice::End => None,
-        }
-    }
-
-    /// Get current value. Always Some(_) unless last call to advance returned something else than
-    /// Ok(true)
-    pub fn value(&self) -> Option<&BlockAddr> {
-        match self {
-            ReaderOrSlice::Reader(reader) => Some(reader.value()),
-            ReaderOrSlice::Iter(slice, index) => Some(&slice[*index].block_addr),
-            ReaderOrSlice::End => None,
-        }
-    }
-}
-
-#[derive(Clone, Eq, PartialEq, Debug)]
-pub struct BlockAddr {
-    pub byte_range: Range<usize>,
-    pub first_ordinal: u64,
-}
-
-#[derive(Debug, Clone)]
-pub(crate) struct BlockMeta {
-    /// Any byte string that is lexicographically greater or equal to
-    /// the last key in the block,
-    /// and yet strictly smaller than the first key in the next block.
-    pub last_key_or_greater: Vec<u8>,
-    pub block_addr: BlockAddr,
-}
-
-#[derive(Default)]
-pub struct SSTableIndexBuilder {
-    index: SSTableIndex,
-}
-
-/// Given that left < right,
-/// mutates `left into a shorter byte string left'` that
-/// matches `left <= left' < right`.
-fn find_shorter_str_in_between(left: &mut Vec<u8>, right: &[u8]) {
-    assert!(&left[..] < right);
-    let common_len = common_prefix_len(left, right);
-    if left.len() == common_len {
-        return;
-    }
-    // It is possible to do one character shorter in some case,
-    // but it is not worth the extra complexity
-    for pos in (common_len + 1)..left.len() {
-        if left[pos] != u8::MAX {
-            left[pos] += 1;
-            left.truncate(pos + 1);
-            return;
-        }
-    }
-}
-
-impl SSTableIndexBuilder {
-    /// In order to make the index as light as possible, we
-    /// try to find a shorter alternative to the last key of the last block
-    /// that is still smaller than the next key.
-    pub(crate) fn shorten_last_block_key_given_next_key(&mut self, next_key: &[u8]) {
-        if let Some(last_block) = self.index.root_blocks.last_mut() {
-            find_shorter_str_in_between(&mut last_block.last_key_or_greater, next_key);
-        }
-    }
-
-    pub fn add_block(&mut self, last_key: &[u8], byte_range: Range<usize>, first_ordinal: u64) {
-        self.index.root_blocks.push(BlockMeta {
-            last_key_or_greater: last_key.to_vec(),
-            block_addr: BlockAddr {
-                byte_range,
-                first_ordinal,
-            },
-        })
-    }
-
-    pub fn serialize<W: std::io::Write>(
-        &self,
-        wrt: W,
-        index_max_root_blocks: std::num::NonZeroU64,
-    ) -> io::Result<(u32, u64)> {
-        let index_max_root_blocks = index_max_root_blocks.get();
-
-        let mut wrt = common::CountingWriter::wrap(wrt);
-        let mut next_layer = write_sstable_layer(&mut wrt, &self.index.root_blocks, 0)?;
-
-        let mut layer_count = 1;
-        let mut offset = 0;
-        while next_layer.len() as u64 > index_max_root_blocks {
-            offset = wrt.written_bytes();
-            layer_count += 1;
-
-            next_layer = write_sstable_layer(&mut wrt, &next_layer, offset as usize)?;
-        }
-        Ok((layer_count, offset))
-    }
-}
-
-fn write_sstable_layer<W: std::io::Write>(
-    wrt: W,
-    layer_content: &[BlockMeta],
-    offset: usize,
-) -> io::Result<Vec<BlockMeta>> {
-    // we can't use a plain writer as it would generate an index
-    // also disable compression, the index is small anyway, and it's the most costly part of
-    // opening that kind of sstable
-    let mut sstable_writer =
-        crate::DeltaWriter::<_, crate::value::index::IndexValueWriter>::new_no_compression(wrt);
-
-    // in tests, set a smaller block size to stress-test
-    #[cfg(test)]
-    sstable_writer.set_block_len(16);
-
-    let mut next_layer = Vec::new();
-    let mut previous_key = Vec::with_capacity(crate::DEFAULT_KEY_CAPACITY);
-    let mut first_ordinal = None;
-    for block in layer_content.iter() {
-        if first_ordinal.is_none() {
-            first_ordinal = Some(block.block_addr.first_ordinal);
-        }
-        let keep_len = common_prefix_len(&previous_key, &block.last_key_or_greater);
-
-        sstable_writer.write_suffix(keep_len, &block.last_key_or_greater[keep_len..]);
-        sstable_writer.write_value(&block.block_addr);
-        if let Some(range) = sstable_writer.flush_block_if_required()? {
-            let real_range = (range.start + offset)..(range.end + offset);
-            let block_meta = BlockMeta {
-                last_key_or_greater: block.last_key_or_greater.clone(),
-                block_addr: BlockAddr {
-                    byte_range: real_range,
-                    first_ordinal: first_ordinal.take().unwrap(),
-                },
-            };
-            next_layer.push(block_meta);
-            previous_key.clear();
-        } else {
-            previous_key.extend_from_slice(&block.last_key_or_greater);
-            previous_key.resize(block.last_key_or_greater.len(), 0u8);
-            previous_key[keep_len..].copy_from_slice(&block.last_key_or_greater[keep_len..]);
-        }
-    }
-    if let Some(range) = sstable_writer.flush_block()? {
-        if let Some(last_block) = layer_content.last() {
-            // not going here means an empty table (?!)
-            let real_range = (range.start + offset)..(range.end + offset);
-            let block_meta = BlockMeta {
-                last_key_or_greater: last_block.last_key_or_greater.clone(),
-                block_addr: BlockAddr {
-                    byte_range: real_range,
-                    first_ordinal: first_ordinal.take().unwrap(),
-                },
-            };
-            next_layer.push(block_meta);
-        }
-    }
-    sstable_writer.finish().write_all(&0u32.to_le_bytes())?;
-
-    Ok(next_layer)
-}
-
-/// SSTable representing an index
-///
-/// `last_key_or_greater` is used as the key, the value contains the
-/// length and first ordinal of each block. The start offset is implicitly
-/// obtained from lengths.
-struct IndexSSTable;
-
-impl SSTable for IndexSSTable {
-    type Value = BlockAddr;
-
-    type ValueReader = crate::value::index::IndexValueReader;
-
-    type ValueWriter = crate::value::index::IndexValueWriter;
-}
-
-#[cfg(test)]
-mod tests {
-    use common::OwnedBytes;
-
-    use super::{BlockAddr, SSTableIndex, SSTableIndexBuilder};
-    use crate::SSTableDataCorruption;
-
-    #[test]
-    fn test_sstable_index() {
-        let mut sstable_builder = SSTableIndexBuilder::default();
-        sstable_builder.add_block(b"aaa", 10..20, 0u64);
-        sstable_builder.add_block(b"bbbbbbb", 20..30, 5u64);
-        sstable_builder.add_block(b"ccc", 30..40, 10u64);
-        sstable_builder.add_block(b"dddd", 40..50, 15u64);
-        let mut buffer: Vec<u8> = Vec::new();
-        sstable_builder
-            .serialize(&mut buffer, crate::DEFAULT_MAX_ROOT_BLOCKS)
-            .unwrap();
-        let buffer = OwnedBytes::new(buffer);
-        let sstable_index = SSTableIndex::load(buffer, 1, 0).unwrap();
-        assert_eq!(
-            sstable_index.get_block_with_key(b"bbbde").unwrap(),
-            Some(BlockAddr {
-                first_ordinal: 10u64,
-                byte_range: 30..40
-            })
-        );
-
-        assert_eq!(
-            sstable_index
-                .get_block_with_key(b"aa")
-                .unwrap()
-                .unwrap()
-                .first_ordinal,
-            0
-        );
-        assert_eq!(
-            sstable_index
-                .get_block_with_key(b"aaa")
-                .unwrap()
-                .unwrap()
-                .first_ordinal,
-            0
-        );
-        assert_eq!(
-            sstable_index
-                .get_block_with_key(b"aab")
-                .unwrap()
-                .unwrap()
-                .first_ordinal,
-            5
-        );
-        assert_eq!(
-            sstable_index
-                .get_block_with_key(b"ccc")
-                .unwrap()
-                .unwrap()
-                .first_ordinal,
-            10
-        );
-        assert!(sstable_index.get_block_with_key(b"e").unwrap().is_none());
-
-        assert_eq!(
-            sstable_index.get_block_with_ord(0).unwrap().first_ordinal,
-            0
-        );
-        assert_eq!(
-            sstable_index.get_block_with_ord(1).unwrap().first_ordinal,
-            0
-        );
-        assert_eq!(
-            sstable_index.get_block_with_ord(4).unwrap().first_ordinal,
-            0
-        );
-        assert_eq!(
-            sstable_index.get_block_with_ord(5).unwrap().first_ordinal,
-            5
-        );
-        assert_eq!(
-            sstable_index.get_block_with_ord(6).unwrap().first_ordinal,
-            5
-        );
-        assert_eq!(
-            sstable_index.get_block_with_ord(100).unwrap().first_ordinal,
-            15
-        );
-    }
-
-    #[test]
-    fn test_sstable_with_corrupted_data() {
-        let mut sstable_builder = SSTableIndexBuilder::default();
-        sstable_builder.add_block(b"aaa", 10..20, 0u64);
-        sstable_builder.add_block(b"bbbbbbb", 20..30, 5u64);
-        sstable_builder.add_block(b"ccc", 30..40, 10u64);
-        sstable_builder.add_block(b"dddd", 40..50, 15u64);
-        let mut buffer: Vec<u8> = Vec::new();
-        sstable_builder
-            .serialize(&mut buffer, crate::DEFAULT_MAX_ROOT_BLOCKS)
-            .unwrap();
-        buffer[2] = 9u8;
-        let buffer = OwnedBytes::new(buffer);
-        let data_corruption_err = SSTableIndex::load(buffer, 1, 0).err().unwrap();
-        assert!(matches!(data_corruption_err, SSTableDataCorruption));
-    }
-
-    #[track_caller]
-    fn test_find_shorter_str_in_between_aux(left: &[u8], right: &[u8]) {
-        let mut left_buf = left.to_vec();
-        super::find_shorter_str_in_between(&mut left_buf, right);
-        assert!(left_buf.len() <= left.len());
-        assert!(left <= &left_buf);
-        assert!(&left_buf[..] < right);
-    }
-
-    #[test]
-    fn test_find_shorter_str_in_between() {
-        test_find_shorter_str_in_between_aux(b"", b"hello");
-        test_find_shorter_str_in_between_aux(b"abc", b"abcd");
-        test_find_shorter_str_in_between_aux(b"abcd", b"abd");
-        test_find_shorter_str_in_between_aux(&[0, 0, 0], &[1]);
-        test_find_shorter_str_in_between_aux(&[0, 0, 0], &[0, 0, 1]);
-        test_find_shorter_str_in_between_aux(&[0, 0, 255, 255, 255, 0u8], &[0, 1]);
-    }
-
-    use proptest::prelude::*;
-
-    proptest! {
-        #![proptest_config(ProptestConfig::with_cases(100))]
-        #[test]
-        fn test_proptest_find_shorter_str(left in any::<Vec<u8>>(), right in any::<Vec<u8>>()) {
-            if left < right {
-                test_find_shorter_str_in_between_aux(&left, &right);
-            }
-        }
-    }
-}

sstable/src/sstable_index_v2.rs

@@ -0,0 +1,101 @@
+use common::OwnedBytes;
+
+use crate::{BlockAddr, SSTable, SSTableDataCorruption, TermOrdinal};
+
+#[derive(Default, Debug, Clone)]
+pub struct SSTableIndex {
+    blocks: Vec<BlockMeta>,
+}
+
+impl SSTableIndex {
+    /// Load an index from its binary representation
+    pub fn load(data: OwnedBytes) -> Result<SSTableIndex, SSTableDataCorruption> {
+        let mut reader = IndexSSTable::reader(data);
+        let mut blocks = Vec::new();
+
+        while reader.advance().map_err(|_| SSTableDataCorruption)? {
+            blocks.push(BlockMeta {
+                last_key_or_greater: reader.key().to_vec(),
+                block_addr: reader.value().clone(),
+            });
+        }
+
+        Ok(SSTableIndex { blocks })
+    }
+
+    /// Get the [`BlockAddr`] of the requested block.
+    pub(crate) fn get_block(&self, block_id: usize) -> Option<BlockAddr> {
+        self.blocks
+            .get(block_id)
+            .map(|block_meta| block_meta.block_addr.clone())
+    }
+
+    /// Get the block id of the block that would contain `key`.
+    ///
+    /// Returns None if `key` is lexicographically after the last key recorded.
+    pub(crate) fn locate_with_key(&self, key: &[u8]) -> Option<usize> {
+        let pos = self
+            .blocks
+            .binary_search_by_key(&key, |block| &block.last_key_or_greater);
+        match pos {
+            Ok(pos) => Some(pos),
+            Err(pos) => {
+                if pos < self.blocks.len() {
+                    Some(pos)
+                } else {
+                    // after end of last block: no block matches
+                    None
+                }
+            }
+        }
+    }
+
+    /// Get the [`BlockAddr`] of the block that would contain `key`.
+    ///
+    /// Returns None if `key` is lexicographically after the last key recorded.
+    pub fn get_block_with_key(&self, key: &[u8]) -> Option<BlockAddr> {
+        self.locate_with_key(key).and_then(|id| self.get_block(id))
+    }
+
+    pub(crate) fn locate_with_ord(&self, ord: TermOrdinal) -> usize {
+        let pos = self
+            .blocks
+            .binary_search_by_key(&ord, |block| block.block_addr.first_ordinal);
+
+        match pos {
+            Ok(pos) => pos,
+            // Err(0) can't happen as the sstable starts with ordinal zero
+            Err(pos) => pos - 1,
+        }
+    }
+
+    /// Get the [`BlockAddr`] of the block containing the `ord`-th term.
+    pub(crate) fn get_block_with_ord(&self, ord: TermOrdinal) -> BlockAddr {
+        // locate_with_ord always returns an index within range
+        self.get_block(self.locate_with_ord(ord)).unwrap()
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct BlockMeta {
+    /// Any byte string that is lexicographically greater or equal to
+    /// the last key in the block,
+    /// and yet strictly smaller than the first key in the next block.
+    pub last_key_or_greater: Vec<u8>,
+    pub block_addr: BlockAddr,
+}
+
+/// SSTable representing an index
+///
+/// `last_key_or_greater` is used as the key, the value contains the
+/// length and first ordinal of each block. The start offset is implicitly
+/// obtained from lengths.
+struct IndexSSTable;
+
+impl SSTable for IndexSSTable {
+    type Value = BlockAddr;
+
+    type ValueReader = crate::value::index::IndexValueReader;
+
+    type ValueWriter = crate::value::index::IndexValueWriter;
+}

sstable/src/sstable_index_v3.rs

@@ -0,0 +1,826 @@
+use std::io::{self, Read, Write};
+use std::ops::Range;
+use std::sync::Arc;
+
+use common::{BinarySerializable, FixedSize, OwnedBytes};
+use tantivy_bitpacker::{compute_num_bits, BitPacker};
+use tantivy_fst::raw::Fst;
+use tantivy_fst::{IntoStreamer, Map, MapBuilder, Streamer};
+
+use crate::{common_prefix_len, SSTableDataCorruption, TermOrdinal};
+
+#[derive(Debug, Clone)]
+pub enum SSTableIndex {
+    V2(crate::sstable_index_v2::SSTableIndex),
+    V3(SSTableIndexV3),
+    V3Empty(SSTableIndexV3Empty),
+}
+
+impl SSTableIndex {
+    /// Get the [`BlockAddr`] of the requested block.
+    pub(crate) fn get_block(&self, block_id: u64) -> Option<BlockAddr> {
+        match self {
+            SSTableIndex::V2(v2_index) => v2_index.get_block(block_id as usize),
+            SSTableIndex::V3(v3_index) => v3_index.get_block(block_id),
+            SSTableIndex::V3Empty(v3_empty) => v3_empty.get_block(block_id),
+        }
+    }
+
+    /// Get the block id of the block that would contain `key`.
+    ///
+    /// Returns None if `key` is lexicographically after the last key recorded.
+    pub(crate) fn locate_with_key(&self, key: &[u8]) -> Option<u64> {
+        match self {
+            SSTableIndex::V2(v2_index) => v2_index.locate_with_key(key).map(|i| i as u64),
+            SSTableIndex::V3(v3_index) => v3_index.locate_with_key(key),
+            SSTableIndex::V3Empty(v3_empty) => v3_empty.locate_with_key(key),
+        }
+    }
+
+    /// Get the [`BlockAddr`] of the block that would contain `key`.
+    ///
+    /// Returns None if `key` is lexicographically after the last key recorded.
+    pub fn get_block_with_key(&self, key: &[u8]) -> Option<BlockAddr> {
+        match self {
+            SSTableIndex::V2(v2_index) => v2_index.get_block_with_key(key),
+            SSTableIndex::V3(v3_index) => v3_index.get_block_with_key(key),
+            SSTableIndex::V3Empty(v3_empty) => v3_empty.get_block_with_key(key),
+        }
+    }
+
+    pub(crate) fn locate_with_ord(&self, ord: TermOrdinal) -> u64 {
+        match self {
+            SSTableIndex::V2(v2_index) => v2_index.locate_with_ord(ord) as u64,
+            SSTableIndex::V3(v3_index) => v3_index.locate_with_ord(ord),
+            SSTableIndex::V3Empty(v3_empty) => v3_empty.locate_with_ord(ord),
+        }
+    }
+
+    /// Get the [`BlockAddr`] of the block containing the `ord`-th term.
+    pub(crate) fn get_block_with_ord(&self, ord: TermOrdinal) -> BlockAddr {
+        match self {
+            SSTableIndex::V2(v2_index) => v2_index.get_block_with_ord(ord),
+            SSTableIndex::V3(v3_index) => v3_index.get_block_with_ord(ord),
+            SSTableIndex::V3Empty(v3_empty) => v3_empty.get_block_with_ord(ord),
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct SSTableIndexV3 {
+    fst_index: Arc<Map<OwnedBytes>>,
+    block_addr_store: BlockAddrStore,
+}
+
+impl SSTableIndexV3 {
+    /// Load an index from its binary representation
+    pub fn load(
+        data: OwnedBytes,
+        fst_length: u64,
+    ) -> Result<SSTableIndexV3, SSTableDataCorruption> {
+        let (fst_slice, block_addr_store_slice) = data.split(fst_length as usize);
+        let fst_index = Fst::new(fst_slice)
+            .map_err(|_| SSTableDataCorruption)?
+            .into();
+        let block_addr_store =
+            BlockAddrStore::open(block_addr_store_slice).map_err(|_| SSTableDataCorruption)?;
+
+        Ok(SSTableIndexV3 {
+            fst_index: Arc::new(fst_index),
+            block_addr_store,
+        })
+    }
+
+    /// Get the [`BlockAddr`] of the requested block.
+    pub(crate) fn get_block(&self, block_id: u64) -> Option<BlockAddr> {
+        self.block_addr_store.get(block_id)
+    }
+
+    /// Get the block id of the block that would contain `key`.
+    ///
+    /// Returns None if `key` is lexicographically after the last key recorded.
+    pub(crate) fn locate_with_key(&self, key: &[u8]) -> Option<u64> {
+        self.fst_index
+            .range()
+            .ge(key)
+            .into_stream()
+            .next()
+            .map(|(_key, id)| id)
+    }
+
+    /// Get the [`BlockAddr`] of the block that would contain `key`.
+    ///
+    /// Returns None if `key` is lexicographically after the last key recorded.
+    pub fn get_block_with_key(&self, key: &[u8]) -> Option<BlockAddr> {
+        self.locate_with_key(key).and_then(|id| self.get_block(id))
+    }
+
+    pub(crate) fn locate_with_ord(&self, ord: TermOrdinal) -> u64 {
+        self.block_addr_store.binary_search_ord(ord).0
+    }
+
+    /// Get the [`BlockAddr`] of the block containing the `ord`-th term.
+    pub(crate) fn get_block_with_ord(&self, ord: TermOrdinal) -> BlockAddr {
+        self.block_addr_store.binary_search_ord(ord).1
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct SSTableIndexV3Empty {
+    block_addr: BlockAddr,
+}
+
+impl SSTableIndexV3Empty {
+    pub fn load(index_start_pos: usize) -> SSTableIndexV3Empty {
+        SSTableIndexV3Empty {
+            block_addr: BlockAddr {
+                first_ordinal: 0,
+                byte_range: 0..index_start_pos,
+            },
+        }
+    }
+
+    /// Get the [`BlockAddr`] of the requested block.
+    pub(crate) fn get_block(&self, _block_id: u64) -> Option<BlockAddr> {
+        Some(self.block_addr.clone())
+    }
+
+    /// Get the block id of the block that would contain `key`.
+    ///
+    /// Returns None if `key` is lexicographically after the last key recorded.
+    pub(crate) fn locate_with_key(&self, _key: &[u8]) -> Option<u64> {
+        Some(0)
+    }
+
+    /// Get the [`BlockAddr`] of the block that would contain `key`.
+    ///
+    /// Returns None if `key` is lexicographically after the last key recorded.
+    pub fn get_block_with_key(&self, _key: &[u8]) -> Option<BlockAddr> {
+        Some(self.block_addr.clone())
+    }
+
+    pub(crate) fn locate_with_ord(&self, _ord: TermOrdinal) -> u64 {
+        0
+    }
+
+    /// Get the [`BlockAddr`] of the block containing the `ord`-th term.
+    pub(crate) fn get_block_with_ord(&self, _ord: TermOrdinal) -> BlockAddr {
+        self.block_addr.clone()
+    }
+}
+#[derive(Clone, Eq, PartialEq, Debug)]
+pub struct BlockAddr {
+    pub first_ordinal: u64,
+    pub byte_range: Range<usize>,
+}
+
+impl BlockAddr {
+    fn to_block_start(&self) -> BlockStartAddr {
+        BlockStartAddr {
+            first_ordinal: self.first_ordinal,
+            byte_range_start: self.byte_range.start,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+struct BlockStartAddr {
+    first_ordinal: u64,
+    byte_range_start: usize,
+}
+
+impl BlockStartAddr {
+    fn to_block_addr(&self, byte_range_end: usize) -> BlockAddr {
+        BlockAddr {
+            first_ordinal: self.first_ordinal,
+            byte_range: self.byte_range_start..byte_range_end,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct BlockMeta {
+    /// Any byte string that is lexicographically greater or equal to
+    /// the last key in the block,
+    /// and yet strictly smaller than the first key in the next block.
+    pub last_key_or_greater: Vec<u8>,
+    pub block_addr: BlockAddr,
+}
+
+impl BinarySerializable for BlockStartAddr {
+    fn serialize<W: Write + ?Sized>(&self, writer: &mut W) -> io::Result<()> {
+        let start = self.byte_range_start as u64;
+        start.serialize(writer)?;
+        self.first_ordinal.serialize(writer)
+    }
+
+    fn deserialize<R: Read>(reader: &mut R) -> io::Result<Self> {
+        let byte_range_start = u64::deserialize(reader)? as usize;
+        let first_ordinal = u64::deserialize(reader)?;
+        Ok(BlockStartAddr {
+            first_ordinal,
+            byte_range_start,
+        })
+    }
+
+    // Provided method
+    fn num_bytes(&self) -> u64 {
+        BlockStartAddr::SIZE_IN_BYTES as u64
+    }
+}
+
+impl FixedSize for BlockStartAddr {
+    const SIZE_IN_BYTES: usize = 2 * u64::SIZE_IN_BYTES;
+}
+
+/// Given that left < right,
+/// mutates `left into a shorter byte string left'` that
+/// matches `left <= left' < right`.
+fn find_shorter_str_in_between(left: &mut Vec<u8>, right: &[u8]) {
+    assert!(&left[..] < right);
+    let common_len = common_prefix_len(left, right);
+    if left.len() == common_len {
+        return;
+    }
+    // It is possible to do one character shorter in some case,
+    // but it is not worth the extra complexity
+    for pos in (common_len + 1)..left.len() {
+        if left[pos] != u8::MAX {
+            left[pos] += 1;
+            left.truncate(pos + 1);
+            return;
+        }
+    }
+}
+
+#[derive(Default)]
+pub struct SSTableIndexBuilder {
+    blocks: Vec<BlockMeta>,
+}
+
+impl SSTableIndexBuilder {
+    /// In order to make the index as light as possible, we
+    /// try to find a shorter alternative to the last key of the last block
+    /// that is still smaller than the next key.
+    pub(crate) fn shorten_last_block_key_given_next_key(&mut self, next_key: &[u8]) {
+        if let Some(last_block) = self.blocks.last_mut() {
+            find_shorter_str_in_between(&mut last_block.last_key_or_greater, next_key);
+        }
+    }
+
+    pub fn add_block(&mut self, last_key: &[u8], byte_range: Range<usize>, first_ordinal: u64) {
+        self.blocks.push(BlockMeta {
+            last_key_or_greater: last_key.to_vec(),
+            block_addr: BlockAddr {
+                byte_range,
+                first_ordinal,
+            },
+        })
+    }
+
+    pub fn serialize<W: std::io::Write>(&self, wrt: W) -> io::Result<u64> {
+        if self.blocks.len() <= 1 {
+            return Ok(0);
+        }
+        let counting_writer = common::CountingWriter::wrap(wrt);
+        let mut map_builder = MapBuilder::new(counting_writer).map_err(fst_error_to_io_error)?;
+        for (i, block) in self.blocks.iter().enumerate() {
+            map_builder
+                .insert(&block.last_key_or_greater, i as u64)
+                .map_err(fst_error_to_io_error)?;
+        }
+        let counting_writer = map_builder.into_inner().map_err(fst_error_to_io_error)?;
+        let written_bytes = counting_writer.written_bytes();
+        let mut wrt = counting_writer.finish();
+
+        let mut block_store_writer = BlockAddrStoreWriter::new();
+        for block in &self.blocks {
+            block_store_writer.write_block_meta(block.block_addr.clone())?;
+        }
+        block_store_writer.serialize(&mut wrt)?;
+
+        Ok(written_bytes)
+    }
+}
+
+fn fst_error_to_io_error(error: tantivy_fst::Error) -> io::Error {
+    match error {
+        tantivy_fst::Error::Fst(fst_error) => io::Error::new(io::ErrorKind::Other, fst_error),
+        tantivy_fst::Error::Io(ioerror) => ioerror,
+    }
+}
+
+const STORE_BLOCK_LEN: usize = 128;
+
+#[derive(Debug)]
+struct BlockAddrBlockMetadata {
+    offset: u64,
+    ref_block_addr: BlockStartAddr,
+    range_start_slope: u32,
+    first_ordinal_slope: u32,
+    range_start_nbits: u8,
+    first_ordinal_nbits: u8,
+    block_len: u16,
+    // these fields are computed on deserialization, and not stored
+    range_shift: i64,
+    ordinal_shift: i64,
+}
+
+impl BlockAddrBlockMetadata {
+    fn num_bits(&self) -> u8 {
+        self.first_ordinal_nbits + self.range_start_nbits
+    }
+
+    fn deserialize_block_addr(&self, data: &[u8], inner_offset: usize) -> Option<BlockAddr> {
+        if inner_offset == 0 {
+            let range_end = self.ref_block_addr.byte_range_start
+                + extract_bits(data, 0, self.range_start_nbits) as usize
+                + self.range_start_slope as usize
+                - self.range_shift as usize;
+            return Some(self.ref_block_addr.to_block_addr(range_end));
+        }
+        let inner_offset = inner_offset - 1;
+        if inner_offset >= self.block_len as usize {
+            return None;
+        }
+        let num_bits = self.num_bits() as usize;
+
+        let range_start_addr = num_bits * inner_offset;
+        let ordinal_addr = range_start_addr + self.range_start_nbits as usize;
+        let range_end_addr = range_start_addr + num_bits;
+
+        if (range_end_addr + self.range_start_nbits as usize + 7) / 8 > data.len() {
+            return None;
+        }
+
+        let range_start = self.ref_block_addr.byte_range_start
+            + extract_bits(data, range_start_addr, self.range_start_nbits) as usize
+            + self.range_start_slope as usize * (inner_offset + 1)
+            - self.range_shift as usize;
+        let first_ordinal = self.ref_block_addr.first_ordinal
+            + extract_bits(data, ordinal_addr, self.first_ordinal_nbits)
+            + self.first_ordinal_slope as u64 * (inner_offset + 1) as u64
+            - self.ordinal_shift as u64;
+        let range_end = self.ref_block_addr.byte_range_start
+            + extract_bits(data, range_end_addr, self.range_start_nbits) as usize
+            + self.range_start_slope as usize * (inner_offset + 2)
+            - self.range_shift as usize;
+
+        Some(BlockAddr {
+            first_ordinal,
+            byte_range: range_start..range_end,
+        })
+    }
+
+    fn bisect_for_ord(&self, data: &[u8], target_ord: TermOrdinal) -> (u64, BlockAddr) {
+        let inner_target_ord = target_ord - self.ref_block_addr.first_ordinal;
+        let num_bits = self.num_bits() as usize;
+        let range_start_nbits = self.range_start_nbits as usize;
+        let get_ord = |index| {
+            extract_bits(
+                data,
+                num_bits * index as usize + range_start_nbits,
+                self.first_ordinal_nbits,
+            ) + self.first_ordinal_slope as u64 * (index + 1)
+                - self.ordinal_shift as u64
+        };
+
+        let inner_offset = match binary_search(self.block_len as u64, |index| {
+            get_ord(index).cmp(&inner_target_ord)
+        }) {
+            Ok(inner_offset) => inner_offset + 1,
+            Err(inner_offset) => inner_offset,
+        };
+        // we can unwrap because inner_offset <= self.block_len
+        (
+            inner_offset,
+            self.deserialize_block_addr(data, inner_offset as usize)
+                .unwrap(),
+        )
+    }
+}
+
+// TODO move this function to tantivy_common?
+#[inline(always)]
+fn extract_bits(data: &[u8], addr_bits: usize, num_bits: u8) -> u64 {
+    assert!(num_bits <= 56);
+    let addr_byte = addr_bits / 8;
+    let bit_shift = (addr_bits % 8) as u64;
+    let val_unshifted_unmasked: u64 = if data.len() >= addr_byte + 8 {
+        let b = data[addr_byte..addr_byte + 8].try_into().unwrap();
+        u64::from_le_bytes(b)
+    } else {
+        // the buffer is not large enough.
+        // Let's copy the few remaining bytes to a 8 byte buffer
+        // padded with 0s.
+        let mut buf = [0u8; 8];
+        let data_to_copy = &data[addr_byte..];
+        let nbytes = data_to_copy.len();
+        buf[..nbytes].copy_from_slice(data_to_copy);
+        u64::from_le_bytes(buf)
+    };
+    let val_shifted_unmasked = val_unshifted_unmasked >> bit_shift;
+    let mask = (1u64 << u64::from(num_bits)) - 1;
+    val_shifted_unmasked & mask
+}
+
+impl BinarySerializable for BlockAddrBlockMetadata {
+    fn serialize<W: Write + ?Sized>(&self, write: &mut W) -> io::Result<()> {
+        self.offset.serialize(write)?;
+        self.ref_block_addr.serialize(write)?;
+        self.range_start_slope.serialize(write)?;
+        self.first_ordinal_slope.serialize(write)?;
+        write.write_all(&[self.first_ordinal_nbits, self.range_start_nbits])?;
+        self.block_len.serialize(write)?;
+        self.num_bits();
+        Ok(())
+    }
+
+    fn deserialize<R: Read>(reader: &mut R) -> io::Result<Self> {
+        let offset = u64::deserialize(reader)?;
+        let ref_block_addr = BlockStartAddr::deserialize(reader)?;
+        let range_start_slope = u32::deserialize(reader)?;
+        let first_ordinal_slope = u32::deserialize(reader)?;
+        let mut buffer = [0u8; 2];
+        reader.read_exact(&mut buffer)?;
+        let first_ordinal_nbits = buffer[0];
+        let range_start_nbits = buffer[1];
+        let block_len = u16::deserialize(reader)?;
+        Ok(BlockAddrBlockMetadata {
+            offset,
+            ref_block_addr,
+            range_start_slope,
+            first_ordinal_slope,
+            range_start_nbits,
+            first_ordinal_nbits,
+            block_len,
+            range_shift: 1 << (range_start_nbits - 1),
+            ordinal_shift: 1 << (first_ordinal_nbits - 1),
+        })
+    }
+}
+
+impl FixedSize for BlockAddrBlockMetadata {
+    const SIZE_IN_BYTES: usize = u64::SIZE_IN_BYTES
+        + BlockStartAddr::SIZE_IN_BYTES
+        + 2 * u32::SIZE_IN_BYTES
+        + 2 * u8::SIZE_IN_BYTES
+        + u16::SIZE_IN_BYTES;
+}
+
+#[derive(Debug, Clone)]
+struct BlockAddrStore {
+    block_meta_bytes: OwnedBytes,
+    addr_bytes: OwnedBytes,
+}
+
+impl BlockAddrStore {
+    fn open(term_info_store_file: OwnedBytes) -> io::Result<BlockAddrStore> {
+        let (mut len_slice, main_slice) = term_info_store_file.split(8);
+        let len = u64::deserialize(&mut len_slice)? as usize;
+        let (block_meta_bytes, addr_bytes) = main_slice.split(len);
+        Ok(BlockAddrStore {
+            block_meta_bytes,
+            addr_bytes,
+        })
+    }
+
+    fn get_block_meta(&self, store_block_id: usize) -> Option<BlockAddrBlockMetadata> {
+        let mut block_data: &[u8] = self
+            .block_meta_bytes
+            .get(store_block_id * BlockAddrBlockMetadata::SIZE_IN_BYTES..)?;
+        BlockAddrBlockMetadata::deserialize(&mut block_data).ok()
+    }
+
+    fn get(&self, block_id: u64) -> Option<BlockAddr> {
+        let store_block_id = (block_id as usize) / STORE_BLOCK_LEN;
+        let inner_offset = (block_id as usize) % STORE_BLOCK_LEN;
+        let block_addr_block_data = self.get_block_meta(store_block_id)?;
+        block_addr_block_data.deserialize_block_addr(
+            &self.addr_bytes[block_addr_block_data.offset as usize..],
+            inner_offset,
+        )
+    }
+
+    fn binary_search_ord(&self, ord: TermOrdinal) -> (u64, BlockAddr) {
+        let max_block =
+            (self.block_meta_bytes.len() / BlockAddrBlockMetadata::SIZE_IN_BYTES) as u64;
+        let get_first_ordinal = |block_id| {
+            // we can unwrap because block_id < max_block
+            self.get(block_id * STORE_BLOCK_LEN as u64)
+                .unwrap()
+                .first_ordinal
+        };
+        let store_block_id =
+            binary_search(max_block, |block_id| get_first_ordinal(block_id).cmp(&ord));
+        let store_block_id = match store_block_id {
+            Ok(store_block_id) => {
+                let block_id = store_block_id * STORE_BLOCK_LEN as u64;
+                // we can unwrap because store_block_id < max_block
+                return (block_id, self.get(block_id).unwrap());
+            }
+            Err(store_block_id) => store_block_id - 1,
+        };
+
+        // we can unwrap because store_block_id < max_block
+        let block_addr_block_data = self.get_block_meta(store_block_id as usize).unwrap();
+        let (inner_offset, block_addr) = block_addr_block_data.bisect_for_ord(
+            &self.addr_bytes[block_addr_block_data.offset as usize..],
+            ord,
+        );
+        (
+            store_block_id * STORE_BLOCK_LEN as u64 + inner_offset,
+            block_addr,
+        )
+    }
+}
+
+fn binary_search(max: u64, cmp_fn: impl Fn(u64) -> std::cmp::Ordering) -> Result<u64, u64> {
+    use std::cmp::Ordering::*;
+    let mut size = max;
+    let mut left = 0;
+    let mut right = size;
+    while left < right {
+        let mid = left + size / 2;
+
+        let cmp = cmp_fn(mid);
+
+        if cmp == Less {
+            left = mid + 1;
+        } else if cmp == Greater {
+            right = mid;
+        } else {
+            return Ok(mid);
+        }
+
+        size = right - left;
+    }
+    Err(left)
+}
+
+struct BlockAddrStoreWriter {
+    buffer_block_metas: Vec<u8>,
+    buffer_addrs: Vec<u8>,
+    block_addrs: Vec<BlockAddr>,
+}
+
+impl BlockAddrStoreWriter {
+    fn new() -> Self {
+        BlockAddrStoreWriter {
+            buffer_block_metas: Vec::new(),
+            buffer_addrs: Vec::new(),
+            block_addrs: Vec::with_capacity(STORE_BLOCK_LEN),
+        }
+    }
+
+    fn flush_block(&mut self) -> io::Result<()> {
+        if self.block_addrs.is_empty() {
+            return Ok(());
+        }
+        let ref_block_addr = self.block_addrs[0].clone();
+
+        for block_addr in &mut self.block_addrs {
+            block_addr.byte_range.start -= ref_block_addr.byte_range.start;
+            block_addr.first_ordinal -= ref_block_addr.first_ordinal;
+        }
+
+        // we are only called if block_addrs is not empty
+        let mut last_block_addr = self.block_addrs.last().unwrap().clone();
+        last_block_addr.byte_range.end -= ref_block_addr.byte_range.start;
+
+        // we skip(1), so we never give an index of 0 to find_best_slope
+        let (range_start_slope, range_start_nbits) = find_best_slope(
+            self.block_addrs
+                .iter()
+                .map(|block| block.byte_range.start as u64)
+                .chain(std::iter::once(last_block_addr.byte_range.end as u64))
+                .enumerate()
+                .skip(1),
+        );
+
+        // we skip(1), so we never give an index of 0 to find_best_slope
+        let (first_ordinal_slope, first_ordinal_nbits) = find_best_slope(
+            self.block_addrs
+                .iter()
+                .map(|block| block.first_ordinal)
+                .enumerate()
+                .skip(1),
+        );
+
+        let range_shift = 1 << (range_start_nbits - 1);
+        let ordinal_shift = 1 << (first_ordinal_nbits - 1);
+
+        let block_addr_block_meta = BlockAddrBlockMetadata {
+            offset: self.buffer_addrs.len() as u64,
+            ref_block_addr: ref_block_addr.to_block_start(),
+            range_start_slope,
+            first_ordinal_slope,
+            range_start_nbits,
+            first_ordinal_nbits,
+            block_len: self.block_addrs.len() as u16 - 1,
+            range_shift,
+            ordinal_shift,
+        };
+        block_addr_block_meta.serialize(&mut self.buffer_block_metas)?;
+
+        let mut bit_packer = BitPacker::new();
+
+        for (i, block_addr) in self.block_addrs.iter().enumerate().skip(1) {
+            let range_pred = (range_start_slope as usize * i) as i64;
+            bit_packer.write(
+                (block_addr.byte_range.start as i64 - range_pred + range_shift) as u64,
+                range_start_nbits,
+                &mut self.buffer_addrs,
+            )?;
+            let first_ordinal_pred = (first_ordinal_slope as u64 * i as u64) as i64;
+            bit_packer.write(
+                (block_addr.first_ordinal as i64 - first_ordinal_pred + ordinal_shift) as u64,
+                first_ordinal_nbits,
+                &mut self.buffer_addrs,
+            )?;
+        }
+
+        let range_pred = (range_start_slope as usize * self.block_addrs.len()) as i64;
+        bit_packer.write(
+            (last_block_addr.byte_range.end as i64 - range_pred + range_shift) as u64,
+            range_start_nbits,
+            &mut self.buffer_addrs,
+        )?;
+        bit_packer.flush(&mut self.buffer_addrs)?;
+
+        self.block_addrs.clear();
+        Ok(())
+    }
+
+    fn write_block_meta(&mut self, block_addr: BlockAddr) -> io::Result<()> {
+        self.block_addrs.push(block_addr);
+        if self.block_addrs.len() >= STORE_BLOCK_LEN {
+            self.flush_block()?;
+        }
+        Ok(())
+    }
+
+    fn serialize<W: std::io::Write>(&mut self, wrt: &mut W) -> io::Result<()> {
+        self.flush_block()?;
+        let len = self.buffer_block_metas.len() as u64;
+        len.serialize(wrt)?;
+        wrt.write_all(&self.buffer_block_metas)?;
+        wrt.write_all(&self.buffer_addrs)?;
+        Ok(())
+    }
+}
+
+/// Given an iterator over (index, value), returns the slope, and number of bits needed to
+/// represente the error to a prediction made by this slope.
+///
+/// The iterator may be empty, but all indexes in it must be non-zero.
+fn find_best_slope(elements: impl Iterator<Item = (usize, u64)> + Clone) -> (u32, u8) {
+    let slope_iterator = elements.clone();
+    let derivation_iterator = elements;
+
+    let mut min_slope_idx = 1;
+    let mut min_slope_val = 0;
+    let mut min_slope = u32::MAX;
+    let mut max_slope_idx = 1;
+    let mut max_slope_val = 0;
+    let mut max_slope = 0;
+    for (index, value) in slope_iterator {
+        let slope = (value / index as u64) as u32;
+        if slope <= min_slope {
+            min_slope = slope;
+            min_slope_idx = index;
+            min_slope_val = value;
+        }
+        if slope >= max_slope {
+            max_slope = slope;
+            max_slope_idx = index;
+            max_slope_val = value;
+        }
+    }
+
+    // above is an heuristic giving the "highest" and "lowest" point. It's imperfect in that in that
+    // a point that appear earlier might have a high slope derivation, but a smaller absolute
+    // derivation than a latter point.
+    // The actual best values can be obtained by using the symplex method, but the improvement is
+    // likely minimal, and computation is way more complexe.
+    //
+    // Assuming these point are the furthest up and down, we find the slope that would cause the
+    // same positive derivation for the highest as negative derivation for the lowest.
+    // A is the optimal slope. B is the derivation to the guess
+    //
+    // 0 = min_slope_val - min_slope_idx * A - B
+    // 0 = max_slope_val - max_slope_idx * A + B
+    //
+    // 0 = min_slope_val + max_slope_val - (min_slope_idx + max_slope_idx) * A
+    // (min_slope_val + max_slope_val) / (min_slope_idx + max_slope_idx) = A
+    //
+    // we actually add some correcting factor to have proper rounding, not truncation.
+
+    let denominator = (min_slope_idx + max_slope_idx) as u64;
+    let final_slope = ((min_slope_val + max_slope_val + denominator / 2) / denominator) as u32;
+
+    // we don't solve for B because our choice of point is suboptimal, so it's actually a lower
+    // bound and we need to iterate to find the actual worst value.
+
+    let max_derivation: u64 = derivation_iterator
+        .map(|(index, value)| (value as i64 - final_slope as i64 * index as i64).unsigned_abs())
+        .max()
+        .unwrap_or(0);
+
+    (final_slope, compute_num_bits(max_derivation) + 1)
+}
+
+#[cfg(test)]
+mod tests {
+    use common::OwnedBytes;
+
+    use super::{BlockAddr, SSTableIndexBuilder, SSTableIndexV3};
+    use crate::SSTableDataCorruption;
+
+    #[test]
+    fn test_sstable_index() {
+        let mut sstable_builder = SSTableIndexBuilder::default();
+        sstable_builder.add_block(b"aaa", 10..20, 0u64);
+        sstable_builder.add_block(b"bbbbbbb", 20..30, 5u64);
+        sstable_builder.add_block(b"ccc", 30..40, 10u64);
+        sstable_builder.add_block(b"dddd", 40..50, 15u64);
+        let mut buffer: Vec<u8> = Vec::new();
+        let fst_len = sstable_builder.serialize(&mut buffer).unwrap();
+        let buffer = OwnedBytes::new(buffer);
+        let sstable_index = SSTableIndexV3::load(buffer, fst_len).unwrap();
+        assert_eq!(
+            sstable_index.get_block_with_key(b"bbbde"),
+            Some(BlockAddr {
+                first_ordinal: 10u64,
+                byte_range: 30..40
+            })
+        );
+
+        assert_eq!(sstable_index.locate_with_key(b"aa").unwrap(), 0);
+        assert_eq!(sstable_index.locate_with_key(b"aaa").unwrap(), 0);
+        assert_eq!(sstable_index.locate_with_key(b"aab").unwrap(), 1);
+        assert_eq!(sstable_index.locate_with_key(b"ccc").unwrap(), 2);
+        assert!(sstable_index.locate_with_key(b"e").is_none());
+
+        assert_eq!(sstable_index.locate_with_ord(0), 0);
+        assert_eq!(sstable_index.locate_with_ord(1), 0);
+        assert_eq!(sstable_index.locate_with_ord(4), 0);
+        assert_eq!(sstable_index.locate_with_ord(5), 1);
+        assert_eq!(sstable_index.locate_with_ord(100), 3);
+    }
+
+    #[test]
+    fn test_sstable_with_corrupted_data() {
+        let mut sstable_builder = SSTableIndexBuilder::default();
+        sstable_builder.add_block(b"aaa", 10..20, 0u64);
+        sstable_builder.add_block(b"bbbbbbb", 20..30, 5u64);
+        sstable_builder.add_block(b"ccc", 30..40, 10u64);
+        sstable_builder.add_block(b"dddd", 40..50, 15u64);
+        let mut buffer: Vec<u8> = Vec::new();
+        let fst_len = sstable_builder.serialize(&mut buffer).unwrap();
+        buffer[2] = 9u8;
+        let buffer = OwnedBytes::new(buffer);
+        let data_corruption_err = SSTableIndexV3::load(buffer, fst_len).err().unwrap();
+        assert!(matches!(data_corruption_err, SSTableDataCorruption));
+    }
+
+    #[track_caller]
+    fn test_find_shorter_str_in_between_aux(left: &[u8], right: &[u8]) {
+        let mut left_buf = left.to_vec();
+        super::find_shorter_str_in_between(&mut left_buf, right);
+        assert!(left_buf.len() <= left.len());
+        assert!(left <= &left_buf);
+        assert!(&left_buf[..] < right);
+    }
+
+    #[test]
+    fn test_find_shorter_str_in_between() {
+        test_find_shorter_str_in_between_aux(b"", b"hello");
+        test_find_shorter_str_in_between_aux(b"abc", b"abcd");
+        test_find_shorter_str_in_between_aux(b"abcd", b"abd");
+        test_find_shorter_str_in_between_aux(&[0, 0, 0], &[1]);
+        test_find_shorter_str_in_between_aux(&[0, 0, 0], &[0, 0, 1]);
+        test_find_shorter_str_in_between_aux(&[0, 0, 255, 255, 255, 0u8], &[0, 1]);
+    }
+
+    use proptest::prelude::*;
+
+    proptest! {
+        #![proptest_config(ProptestConfig::with_cases(100))]
+        #[test]
+        fn test_proptest_find_shorter_str(left in any::<Vec<u8>>(), right in any::<Vec<u8>>()) {
+            if left < right {
+                test_find_shorter_str_in_between_aux(&left, &right);
+            }
+        }
+    }
+
+    #[test]
+    fn test_find_best_slop() {
+        assert_eq!(super::find_best_slope(std::iter::empty()), (0, 1));
+        assert_eq!(
+            super::find_best_slope(std::iter::once((1, 12345))),
+            (12345, 1)
+        );
+    }
+}

sstable/src/streamer.rs

@@ -110,7 +110,7 @@ where
             Bound::Included(key) | Bound::Excluded(key) => self
                 .term_dict
                 .sstable_index
-                .get_block_with_key(key)?
+                .get_block_with_key(key)
                 .map(|block| block.first_ordinal)
                 .unwrap_or(0),
             Bound::Unbounded => 0,

sstable/src/value/index.rs

@@ -3,10 +3,6 @@ use std::io;
 use crate::value::{deserialize_vint_u64, ValueReader, ValueWriter};
 use crate::{vint, BlockAddr};
 
-// TODO define a LazyIndexValueReader?
-// one which keeps state could be useful for ord_to_block fns,
-// one which doesn't at all woud be perfect for term_to_block fns
-// pending bench to asses real impact
 #[derive(Default)]
 pub(crate) struct IndexValueReader {
     vals: Vec<BlockAddr>,

stacker/src/arena_hashmap.rs

@@ -1,51 +1,5 @@
-use std::iter::{Cloned, Filter};
-use std::mem;
-
 use super::{Addr, MemoryArena};
-use crate::fastcpy::fast_short_slice_copy;
-use crate::memory_arena::store;
-
-/// Returns the actual memory size in bytes
-/// required to create a table with a given capacity.
-/// required to create a table of size
-pub fn compute_table_memory_size(capacity: usize) -> usize {
-    capacity * mem::size_of::<KeyValue>()
-}
-
-#[cfg(not(feature = "compare_hash_only"))]
-type HashType = u32;
-
-#[cfg(feature = "compare_hash_only")]
-type HashType = u64;
-
-/// `KeyValue` is the item stored in the hash table.
-/// The key is actually a `BytesRef` object stored in an external memory arena.
-/// The `value_addr` also points to an address in the memory arena.
-#[derive(Copy, Clone)]
-struct KeyValue {
-    pub(crate) key_value_addr: Addr,
-    hash: HashType,
-}
-
-impl Default for KeyValue {
-    fn default() -> Self {
-        KeyValue {
-            key_value_addr: Addr::null_pointer(),
-            hash: 0,
-        }
-    }
-}
-
-impl KeyValue {
-    #[inline]
-    fn is_empty(&self) -> bool {
-        self.key_value_addr.is_null()
-    }
-    #[inline]
-    fn is_not_empty_ref(&self) -> bool {
-        !self.key_value_addr.is_null()
-    }
-}
+use crate::shared_arena_hashmap::SharedArenaHashMap;
 
 /// Customized `HashMap` with `&[u8]` keys
 ///
@@ -56,61 +10,13 @@ impl KeyValue {
 /// The quirky API has the benefit of avoiding
 /// the computation of the hash of the key twice,
 /// or copying the key as long as there is no insert.
-pub struct ArenaHashMap {
-    table: Vec<KeyValue>,
-    pub memory_arena: MemoryArena,
-    mask: usize,
-    len: usize,
-}
-
-struct LinearProbing {
-    pos: usize,
-    mask: usize,
-}
-
-impl LinearProbing {
-    #[inline]
-    fn compute(hash: HashType, mask: usize) -> LinearProbing {
-        LinearProbing {
-            pos: hash as usize,
-            mask,
-        }
-    }
-
-    #[inline]
-    fn next_probe(&mut self) -> usize {
-        // Not saving the masked version removes a dependency.
-        self.pos = self.pos.wrapping_add(1);
-        self.pos & self.mask
-    }
-}
-
-type IterNonEmpty<'a> = Filter<Cloned<std::slice::Iter<'a, KeyValue>>, fn(&KeyValue) -> bool>;
-
-pub struct Iter<'a> {
-    hashmap: &'a ArenaHashMap,
-    inner: IterNonEmpty<'a>,
-}
-
-impl<'a> Iterator for Iter<'a> {
-    type Item = (&'a [u8], Addr);
-
-    fn next(&mut self) -> Option<Self::Item> {
-        self.inner.next().map(move |kv| {
-            let (key, offset): (&'a [u8], Addr) = self.hashmap.get_key_value(kv.key_value_addr);
-            (key, offset)
-        })
-    }
-}
-
-/// Returns the greatest power of two lower or equal to `n`.
-/// Except if n == 0, in that case, return 1.
 ///
-/// # Panics if n == 0
-fn compute_previous_power_of_two(n: usize) -> usize {
-    assert!(n > 0);
-    let msb = (63u32 - (n as u64).leading_zeros()) as u8;
-    1 << msb
+/// ArenaHashMap is like SharedArenaHashMap but takes ownership
+/// of the memory arena. The memory arena stores the serialized
+/// keys and values.
+pub struct ArenaHashMap {
+    shared_arena_hashmap: SharedArenaHashMap,
+    pub memory_arena: MemoryArena,
 }
 
 impl Default for ArenaHashMap {
@@ -121,156 +27,44 @@ impl Default for ArenaHashMap {
 
 impl ArenaHashMap {
     pub fn with_capacity(table_size: usize) -> ArenaHashMap {
-        let table_size_power_of_2 = compute_previous_power_of_two(table_size);
         let memory_arena = MemoryArena::default();
-        let table = vec![KeyValue::default(); table_size_power_of_2];
 
         ArenaHashMap {
-            table,
+            shared_arena_hashmap: SharedArenaHashMap::with_capacity(table_size),
             memory_arena,
-            mask: table_size_power_of_2 - 1,
-            len: 0,
         }
     }
 
-    #[inline]
-    #[cfg(not(feature = "compare_hash_only"))]
-    fn get_hash(&self, key: &[u8]) -> HashType {
-        murmurhash32::murmurhash2(key)
-    }
-
-    #[inline]
-    #[cfg(feature = "compare_hash_only")]
-    fn get_hash(&self, key: &[u8]) -> HashType {
-        /// Since we compare only the hash we need a high quality hash.
-        use std::hash::Hasher;
-        let mut hasher = ahash::AHasher::default();
-        hasher.write(key);
-        hasher.finish() as HashType
-    }
-
     #[inline]
     pub fn read<Item: Copy + 'static>(&self, addr: Addr) -> Item {
         self.memory_arena.read(addr)
     }
 
-    #[inline]
-    fn probe(&self, hash: HashType) -> LinearProbing {
-        LinearProbing::compute(hash, self.mask)
-    }
-
     #[inline]
     pub fn mem_usage(&self) -> usize {
-        self.table.len() * mem::size_of::<KeyValue>() + self.memory_arena.mem_usage()
-    }
-
-    #[inline]
-    fn is_saturated(&self) -> bool {
-        self.table.len() <= self.len * 2
-    }
-
-    #[inline]
-    fn get_key_value(&self, addr: Addr) -> (&[u8], Addr) {
-        let data = self.memory_arena.slice_from(addr);
-        let key_bytes_len_bytes = unsafe { data.get_unchecked(..2) };
-        let key_bytes_len = u16::from_le_bytes(key_bytes_len_bytes.try_into().unwrap());
-        let key_bytes: &[u8] = unsafe { data.get_unchecked(2..2 + key_bytes_len as usize) };
-        (key_bytes, addr.offset(2 + key_bytes_len as u32))
-    }
-
-    #[inline]
-    #[cfg(not(feature = "compare_hash_only"))]
-    fn get_value_addr_if_key_match(&self, target_key: &[u8], addr: Addr) -> Option<Addr> {
-        use crate::fastcmp::fast_short_slice_compare;
-
-        let (stored_key, value_addr) = self.get_key_value(addr);
-        if fast_short_slice_compare(stored_key, target_key) {
-            Some(value_addr)
-        } else {
-            None
-        }
-    }
-    #[inline]
-    #[cfg(feature = "compare_hash_only")]
-    fn get_value_addr_if_key_match(&self, _target_key: &[u8], addr: Addr) -> Option<Addr> {
-        // For the compare_hash_only feature, it would make sense to store the keys at a different
-        // memory location. Here they will just pollute the cache.
-        let data = self.memory_arena.slice_from(addr);
-        let key_bytes_len_bytes = &data[..2];
-        let key_bytes_len = u16::from_le_bytes(key_bytes_len_bytes.try_into().unwrap());
-        let value_addr = addr.offset(2 + key_bytes_len as u32);
-
-        Some(value_addr)
-    }
-
-    #[inline]
-    fn set_bucket(&mut self, hash: HashType, key_value_addr: Addr, bucket: usize) {
-        self.len += 1;
-
-        self.table[bucket] = KeyValue {
-            key_value_addr,
-            hash,
-        };
+        self.shared_arena_hashmap.mem_usage() + self.memory_arena.mem_usage()
     }
 
     #[inline]
     pub fn is_empty(&self) -> bool {
-        self.len() == 0
+        self.shared_arena_hashmap.is_empty()
     }
 
     #[inline]
     pub fn len(&self) -> usize {
-        self.len
+        self.shared_arena_hashmap.len()
     }
 
     #[inline]
-    pub fn iter(&self) -> Iter<'_> {
-        Iter {
-            inner: self
-                .table
-                .iter()
-                .cloned()
-                .filter(KeyValue::is_not_empty_ref),
-            hashmap: self,
-        }
-    }
-
-    fn resize(&mut self) {
-        let new_len = (self.table.len() * 2).max(1 << 13);
-        let mask = new_len - 1;
-        self.mask = mask;
-        let new_table = vec![KeyValue::default(); new_len];
-        let old_table = mem::replace(&mut self.table, new_table);
-        for key_value in old_table.into_iter().filter(KeyValue::is_not_empty_ref) {
-            let mut probe = LinearProbing::compute(key_value.hash, mask);
-            loop {
-                let bucket = probe.next_probe();
-                if self.table[bucket].is_empty() {
-                    self.table[bucket] = key_value;
-                    break;
-                }
-            }
-        }
+    pub fn iter(&self) -> impl Iterator<Item = (&[u8], Addr)> {
+        self.shared_arena_hashmap.iter(&self.memory_arena)
     }
 
     /// Get a value associated to a key.
     #[inline]
     pub fn get<V>(&self, key: &[u8]) -> Option<V>
     where V: Copy + 'static {
-        let hash = self.get_hash(key);
-        let mut probe = self.probe(hash);
-        loop {
-            let bucket = probe.next_probe();
-            let kv: KeyValue = self.table[bucket];
-            if kv.is_empty() {
-                return None;
-            } else if kv.hash == hash {
-                if let Some(val_addr) = self.get_value_addr_if_key_match(key, kv.key_value_addr) {
-                    let v = self.memory_arena.read(val_addr);
-                    return Some(v);
-                }
-            }
-        }
+        self.shared_arena_hashmap.get(key, &self.memory_arena)
     }
 
     /// `update` create a new entry for a given key if it does not exist
@@ -284,45 +78,10 @@ impl ArenaHashMap {
     /// If the key already as an associated value, then it will be passed
     /// `Some(previous_value)`.
     #[inline]
-    pub fn mutate_or_create<V>(&mut self, key: &[u8], mut updater: impl FnMut(Option<V>) -> V)
+    pub fn mutate_or_create<V>(&mut self, key: &[u8], updater: impl FnMut(Option<V>) -> V)
     where V: Copy + 'static {
-        if self.is_saturated() {
-            self.resize();
-        }
-        let hash = self.get_hash(key);
-        let mut probe = self.probe(hash);
-        let mut bucket = probe.next_probe();
-        let mut kv: KeyValue = self.table[bucket];
-        loop {
-            if kv.is_empty() {
-                // The key does not exist yet.
-                let val = updater(None);
-                let num_bytes = std::mem::size_of::<u16>() + key.len() + std::mem::size_of::<V>();
-                let key_addr = self.memory_arena.allocate_space(num_bytes);
-                {
-                    let data = self.memory_arena.slice_mut(key_addr, num_bytes);
-                    let key_len_bytes: [u8; 2] = (key.len() as u16).to_le_bytes();
-                    data[..2].copy_from_slice(&key_len_bytes);
-                    let stop = 2 + key.len();
-                    fast_short_slice_copy(key, &mut data[2..stop]);
-                    store(&mut data[stop..], val);
-                }
-
-                self.set_bucket(hash, key_addr, bucket);
-                return;
-            }
-            if kv.hash == hash {
-                if let Some(val_addr) = self.get_value_addr_if_key_match(key, kv.key_value_addr) {
-                    let v = self.memory_arena.read(val_addr);
-                    let new_v = updater(Some(v));
-                    self.memory_arena.write_at(val_addr, new_v);
-                    return;
-                }
-            }
-            // This allows fetching the next bucket before the loop jmp
-            bucket = probe.next_probe();
-            kv = self.table[bucket];
-        }
+        self.shared_arena_hashmap
+            .mutate_or_create(key, &mut self.memory_arena, updater);
     }
 }
 
@@ -331,7 +90,7 @@ mod tests {
 
     use std::collections::HashMap;
 
-    use super::{compute_previous_power_of_two, ArenaHashMap};
+    use super::ArenaHashMap;
 
     #[test]
     fn test_hash_map() {
@@ -362,14 +121,6 @@ mod tests {
         assert_eq!(hash_map.get::<u32>(b"abc"), None);
     }
 
-    #[test]
-    fn test_compute_previous_power_of_two() {
-        assert_eq!(compute_previous_power_of_two(8), 8);
-        assert_eq!(compute_previous_power_of_two(9), 8);
-        assert_eq!(compute_previous_power_of_two(7), 4);
-        assert_eq!(compute_previous_power_of_two(u64::MAX as usize), 1 << 63);
-    }
-
     #[test]
     fn test_many_terms() {
         let mut terms: Vec<String> = (0..20_000).map(|val| val.to_string()).collect();

stacker/src/lib.rs

@@ -9,10 +9,12 @@ mod expull;
 mod fastcmp;
 mod fastcpy;
 mod memory_arena;
+mod shared_arena_hashmap;
 
-pub use self::arena_hashmap::{compute_table_memory_size, ArenaHashMap};
+pub use self::arena_hashmap::ArenaHashMap;
 pub use self::expull::ExpUnrolledLinkedList;
 pub use self::memory_arena::{Addr, MemoryArena};
+pub use self::shared_arena_hashmap::{compute_table_memory_size, SharedArenaHashMap};
 
 /// When adding an element in a `ArenaHashMap`, we get a unique id associated to the given key.
 pub type UnorderedId = u32;

stacker/src/shared_arena_hashmap.rs

@@ -0,0 +1,420 @@
+use std::iter::{Cloned, Filter};
+use std::mem;
+
+use super::{Addr, MemoryArena};
+use crate::fastcpy::fast_short_slice_copy;
+use crate::memory_arena::store;
+
+/// Returns the actual memory size in bytes
+/// required to create a table with a given capacity.
+/// required to create a table of size
+pub fn compute_table_memory_size(capacity: usize) -> usize {
+    capacity * mem::size_of::<KeyValue>()
+}
+
+#[cfg(not(feature = "compare_hash_only"))]
+type HashType = u32;
+
+#[cfg(feature = "compare_hash_only")]
+type HashType = u64;
+
+/// `KeyValue` is the item stored in the hash table.
+/// The key is actually a `BytesRef` object stored in an external memory arena.
+/// The `value_addr` also points to an address in the memory arena.
+#[derive(Copy, Clone)]
+struct KeyValue {
+    key_value_addr: Addr,
+    hash: HashType,
+}
+
+impl Default for KeyValue {
+    fn default() -> Self {
+        KeyValue {
+            key_value_addr: Addr::null_pointer(),
+            hash: 0,
+        }
+    }
+}
+
+impl KeyValue {
+    #[inline]
+    fn is_empty(&self) -> bool {
+        self.key_value_addr.is_null()
+    }
+    #[inline]
+    fn is_not_empty_ref(&self) -> bool {
+        !self.key_value_addr.is_null()
+    }
+}
+
+/// Customized `HashMap` with `&[u8]` keys
+///
+/// Its main particularity is that rather than storing its
+/// keys in the heap, keys are stored in a memory arena
+/// inline with the values.
+///
+/// The quirky API has the benefit of avoiding
+/// the computation of the hash of the key twice,
+/// or copying the key as long as there is no insert.
+///
+/// SharedArenaHashMap is like ArenaHashMap but gets the memory arena
+/// passed as an argument to the methods.
+/// So one MemoryArena can be shared with multiple SharedArenaHashMap.
+pub struct SharedArenaHashMap {
+    table: Vec<KeyValue>,
+    mask: usize,
+    len: usize,
+}
+
+struct LinearProbing {
+    pos: usize,
+    mask: usize,
+}
+
+impl LinearProbing {
+    #[inline]
+    fn compute(hash: HashType, mask: usize) -> LinearProbing {
+        LinearProbing {
+            pos: hash as usize,
+            mask,
+        }
+    }
+
+    #[inline]
+    fn next_probe(&mut self) -> usize {
+        // Not saving the masked version removes a dependency.
+        self.pos = self.pos.wrapping_add(1);
+        self.pos & self.mask
+    }
+}
+
+type IterNonEmpty<'a> = Filter<Cloned<std::slice::Iter<'a, KeyValue>>, fn(&KeyValue) -> bool>;
+
+pub struct Iter<'a> {
+    hashmap: &'a SharedArenaHashMap,
+    memory_arena: &'a MemoryArena,
+    inner: IterNonEmpty<'a>,
+}
+
+impl<'a> Iterator for Iter<'a> {
+    type Item = (&'a [u8], Addr);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next().map(move |kv| {
+            let (key, offset): (&'a [u8], Addr) = self
+                .hashmap
+                .get_key_value(kv.key_value_addr, self.memory_arena);
+            (key, offset)
+        })
+    }
+}
+
+/// Returns the greatest power of two lower or equal to `n`.
+/// Except if n == 0, in that case, return 1.
+///
+/// # Panics if n == 0
+fn compute_previous_power_of_two(n: usize) -> usize {
+    assert!(n > 0);
+    let msb = (63u32 - (n as u64).leading_zeros()) as u8;
+    1 << msb
+}
+
+impl Default for SharedArenaHashMap {
+    fn default() -> Self {
+        SharedArenaHashMap::with_capacity(4)
+    }
+}
+
+impl SharedArenaHashMap {
+    pub fn with_capacity(table_size: usize) -> SharedArenaHashMap {
+        let table_size_power_of_2 = compute_previous_power_of_two(table_size);
+        let table = vec![KeyValue::default(); table_size_power_of_2];
+
+        SharedArenaHashMap {
+            table,
+            mask: table_size_power_of_2 - 1,
+            len: 0,
+        }
+    }
+
+    #[inline]
+    #[cfg(not(feature = "compare_hash_only"))]
+    fn get_hash(&self, key: &[u8]) -> HashType {
+        murmurhash32::murmurhash2(key)
+    }
+
+    #[inline]
+    #[cfg(feature = "compare_hash_only")]
+    fn get_hash(&self, key: &[u8]) -> HashType {
+        /// Since we compare only the hash we need a high quality hash.
+        use std::hash::Hasher;
+        let mut hasher = ahash::AHasher::default();
+        hasher.write(key);
+        hasher.finish() as HashType
+    }
+
+    #[inline]
+    fn probe(&self, hash: HashType) -> LinearProbing {
+        LinearProbing::compute(hash, self.mask)
+    }
+
+    #[inline]
+    pub fn mem_usage(&self) -> usize {
+        self.table.len() * mem::size_of::<KeyValue>()
+    }
+
+    #[inline]
+    fn is_saturated(&self) -> bool {
+        self.table.len() <= self.len * 2
+    }
+
+    #[inline]
+    fn get_key_value<'a>(&'a self, addr: Addr, memory_arena: &'a MemoryArena) -> (&[u8], Addr) {
+        let data = memory_arena.slice_from(addr);
+        let key_bytes_len_bytes = unsafe { data.get_unchecked(..2) };
+        let key_bytes_len = u16::from_le_bytes(key_bytes_len_bytes.try_into().unwrap());
+        let key_bytes: &[u8] = unsafe { data.get_unchecked(2..2 + key_bytes_len as usize) };
+        (key_bytes, addr.offset(2 + key_bytes_len as u32))
+    }
+
+    #[inline]
+    #[cfg(not(feature = "compare_hash_only"))]
+    fn get_value_addr_if_key_match(
+        &self,
+        target_key: &[u8],
+        addr: Addr,
+        memory_arena: &MemoryArena,
+    ) -> Option<Addr> {
+        use crate::fastcmp::fast_short_slice_compare;
+
+        let (stored_key, value_addr) = self.get_key_value(addr, memory_arena);
+        if fast_short_slice_compare(stored_key, target_key) {
+            Some(value_addr)
+        } else {
+            None
+        }
+    }
+    #[inline]
+    #[cfg(feature = "compare_hash_only")]
+    fn get_value_addr_if_key_match(
+        &self,
+        _target_key: &[u8],
+        addr: Addr,
+        memory_arena: &MemoryArena,
+    ) -> Option<Addr> {
+        // For the compare_hash_only feature, it would make sense to store the keys at a different
+        // memory location. Here they will just pollute the cache.
+        let data = memory_arena.slice_from(addr);
+        let key_bytes_len_bytes = &data[..2];
+        let key_bytes_len = u16::from_le_bytes(key_bytes_len_bytes.try_into().unwrap());
+        let value_addr = addr.offset(2 + key_bytes_len as u32);
+
+        Some(value_addr)
+    }
+
+    #[inline]
+    fn set_bucket(&mut self, hash: HashType, key_value_addr: Addr, bucket: usize) {
+        self.len += 1;
+
+        self.table[bucket] = KeyValue {
+            key_value_addr,
+            hash,
+        };
+    }
+
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    #[inline]
+    pub fn len(&self) -> usize {
+        self.len
+    }
+
+    #[inline]
+    pub fn iter<'a>(&'a self, memory_arena: &'a MemoryArena) -> Iter<'_> {
+        Iter {
+            inner: self
+                .table
+                .iter()
+                .cloned()
+                .filter(KeyValue::is_not_empty_ref),
+            hashmap: self,
+            memory_arena,
+        }
+    }
+
+    fn resize(&mut self) {
+        let new_len = (self.table.len() * 2).max(1 << 3);
+        let mask = new_len - 1;
+        self.mask = mask;
+        let new_table = vec![KeyValue::default(); new_len];
+        let old_table = mem::replace(&mut self.table, new_table);
+        for key_value in old_table.into_iter().filter(KeyValue::is_not_empty_ref) {
+            let mut probe = LinearProbing::compute(key_value.hash, mask);
+            loop {
+                let bucket = probe.next_probe();
+                if self.table[bucket].is_empty() {
+                    self.table[bucket] = key_value;
+                    break;
+                }
+            }
+        }
+    }
+
+    /// Get a value associated to a key.
+    #[inline]
+    pub fn get<V>(&self, key: &[u8], memory_arena: &MemoryArena) -> Option<V>
+    where V: Copy + 'static {
+        let hash = self.get_hash(key);
+        let mut probe = self.probe(hash);
+        loop {
+            let bucket = probe.next_probe();
+            let kv: KeyValue = self.table[bucket];
+            if kv.is_empty() {
+                return None;
+            } else if kv.hash == hash {
+                if let Some(val_addr) =
+                    self.get_value_addr_if_key_match(key, kv.key_value_addr, memory_arena)
+                {
+                    let v = memory_arena.read(val_addr);
+                    return Some(v);
+                }
+            }
+        }
+    }
+
+    /// `update` create a new entry for a given key if it does not exist
+    /// or updates the existing entry.
+    ///
+    /// The actual logic for this update is define in the `updater`
+    /// argument.
+    ///
+    /// If the key is not present, `updater` will receive `None` and
+    /// will be in charge of returning a default value.
+    /// If the key already as an associated value, then it will be passed
+    /// `Some(previous_value)`.
+    #[inline]
+    pub fn mutate_or_create<V>(
+        &mut self,
+        key: &[u8],
+        memory_arena: &mut MemoryArena,
+        mut updater: impl FnMut(Option<V>) -> V,
+    ) -> V
+    where
+        V: Copy + 'static,
+    {
+        if self.is_saturated() {
+            self.resize();
+        }
+        let hash = self.get_hash(key);
+        let mut probe = self.probe(hash);
+        let mut bucket = probe.next_probe();
+        let mut kv: KeyValue = self.table[bucket];
+        loop {
+            if kv.is_empty() {
+                // The key does not exist yet.
+                let val = updater(None);
+                let num_bytes = std::mem::size_of::<u16>() + key.len() + std::mem::size_of::<V>();
+                let key_addr = memory_arena.allocate_space(num_bytes);
+                {
+                    let data = memory_arena.slice_mut(key_addr, num_bytes);
+                    let key_len_bytes: [u8; 2] = (key.len() as u16).to_le_bytes();
+                    data[..2].copy_from_slice(&key_len_bytes);
+                    let stop = 2 + key.len();
+                    fast_short_slice_copy(key, &mut data[2..stop]);
+                    store(&mut data[stop..], val);
+                }
+
+                self.set_bucket(hash, key_addr, bucket);
+                return val;
+            }
+            if kv.hash == hash {
+                if let Some(val_addr) =
+                    self.get_value_addr_if_key_match(key, kv.key_value_addr, memory_arena)
+                {
+                    let v = memory_arena.read(val_addr);
+                    let new_v = updater(Some(v));
+                    memory_arena.write_at(val_addr, new_v);
+                    return new_v;
+                }
+            }
+            // This allows fetching the next bucket before the loop jmp
+            bucket = probe.next_probe();
+            kv = self.table[bucket];
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+
+    use std::collections::HashMap;
+
+    use super::{compute_previous_power_of_two, SharedArenaHashMap};
+    use crate::MemoryArena;
+
+    #[test]
+    fn test_hash_map() {
+        let mut memory_arena = MemoryArena::default();
+        let mut hash_map: SharedArenaHashMap = SharedArenaHashMap::default();
+        hash_map.mutate_or_create(b"abc", &mut memory_arena, |opt_val: Option<u32>| {
+            assert_eq!(opt_val, None);
+            3u32
+        });
+        hash_map.mutate_or_create(b"abcd", &mut memory_arena, |opt_val: Option<u32>| {
+            assert_eq!(opt_val, None);
+            4u32
+        });
+        hash_map.mutate_or_create(b"abc", &mut memory_arena, |opt_val: Option<u32>| {
+            assert_eq!(opt_val, Some(3u32));
+            5u32
+        });
+        let mut vanilla_hash_map = HashMap::new();
+        let iter_values = hash_map.iter(&memory_arena);
+        for (key, addr) in iter_values {
+            let val: u32 = memory_arena.read(addr);
+            vanilla_hash_map.insert(key.to_owned(), val);
+        }
+        assert_eq!(vanilla_hash_map.len(), 2);
+    }
+    #[test]
+    fn test_empty_hashmap() {
+        let memory_arena = MemoryArena::default();
+        let hash_map: SharedArenaHashMap = SharedArenaHashMap::default();
+        assert_eq!(hash_map.get::<u32>(b"abc", &memory_arena), None);
+    }
+
+    #[test]
+    fn test_compute_previous_power_of_two() {
+        assert_eq!(compute_previous_power_of_two(8), 8);
+        assert_eq!(compute_previous_power_of_two(9), 8);
+        assert_eq!(compute_previous_power_of_two(7), 4);
+        assert_eq!(compute_previous_power_of_two(u64::MAX as usize), 1 << 63);
+    }
+
+    #[test]
+    fn test_many_terms() {
+        let mut memory_arena = MemoryArena::default();
+        let mut terms: Vec<String> = (0..20_000).map(|val| val.to_string()).collect();
+        let mut hash_map: SharedArenaHashMap = SharedArenaHashMap::default();
+        for term in terms.iter() {
+            hash_map.mutate_or_create(
+                term.as_bytes(),
+                &mut memory_arena,
+                |_opt_val: Option<u32>| 5u32,
+            );
+        }
+        let mut terms_back: Vec<String> = hash_map
+            .iter(&memory_arena)
+            .map(|(bytes, _)| String::from_utf8(bytes.to_vec()).unwrap())
+            .collect();
+        terms_back.sort();
+        terms.sort();
+
+        for pos in 0..terms.len() {
+            assert_eq!(terms[pos], terms_back[pos]);
+        }
+    }
+}