Added simple columnar CLI program

See README for more information.

.gitignore

@@ -13,3 +13,5 @@ benchmark
 .idea
 trace.dat
 cargo-timing*
+columnar/columnar-cli/*.json
+**/perf.data*

Cargo.toml

@@ -36,7 +36,6 @@ fs2 = { version = "0.4.3", optional = true }
 levenshtein_automata = "0.2.1"
 uuid = { version = "1.0.0", features = ["v4", "serde"] }
 crossbeam-channel = "0.5.4"
-stable_deref_trait = "1.2.0"
 rust-stemmers = "1.2.0"
 downcast-rs = "1.2.0"
 bitpacking = { version = "0.8.4", default-features = false, features = ["bitpacker4x"] }
@@ -62,7 +61,6 @@ tantivy-query-grammar = { version= "0.19.0", path="./query-grammar" }
 tantivy-bitpacker = 		{ version= "0.3", path="./bitpacker" }
 common = 								{ version= "0.5", path = "./common/", package = "tantivy-common" }
 fastfield_codecs = 			{ version= "0.3", path="./fastfield_codecs", default-features = false }
-ownedbytes = 						{ version= "0.5", path="./ownedbytes" }
 
 [target.'cfg(windows)'.dependencies]
 winapi = "0.3.9"

bitpacker/src/bitpacker.rs

@@ -91,17 +91,15 @@ impl BitUnpacker {
             return 0u64;
         }
         let addr_in_bits = idx * self.num_bits as u32;
-        let addr = addr_in_bits >> 3;
+        let addr = (addr_in_bits >> 3) as usize;
         let bit_shift = addr_in_bits & 7;
         debug_assert!(
-            addr + 8 <= data.len() as u32,
+            addr + 8 <= data.len(),
             "The fast field field should have been padded with 7 bytes."
         );
-        let bytes: [u8; 8] = (&data[(addr as usize)..(addr as usize) + 8])
-            .try_into()
-            .unwrap();
+        let bytes: [u8; 8] = (&data[addr..addr + 8]).try_into().unwrap();
         let val_unshifted_unmasked: u64 = u64::from_le_bytes(bytes);
-        let val_shifted: u64 = val_unshifted_unmasked >> bit_shift;
+        let val_shifted = val_unshifted_unmasked >> bit_shift;
         val_shifted & self.mask
     }
 }

bitpacker/src/lib.rs

@@ -1,6 +1,8 @@
 mod bitpacker;
 mod blocked_bitpacker;
 
+use std::cmp::Ordering;
+
 pub use crate::bitpacker::{BitPacker, BitUnpacker};
 pub use crate::blocked_bitpacker::BlockedBitpacker;
 
@@ -37,44 +39,104 @@ pub fn compute_num_bits(n: u64) -> u8 {
     }
 }
 
+/// Computes the (min, max) of an iterator of `PartialOrd` values.
+///
+/// For values implementing `Ord` (in a way consistent to their `PartialOrd` impl),
+/// this function behaves as expected.
+///
+/// For values with partial ordering, the behavior is non-trivial and may
+/// depends on the order of the values.
+/// For floats however, it simply returns the same results as if NaN were
+/// skipped.
 pub fn minmax<I, T>(mut vals: I) -> Option<(T, T)>
 where
     I: Iterator<Item = T>,
-    T: Copy + Ord,
+    T: Copy + PartialOrd,
 {
-    if let Some(first_el) = vals.next() {
-        return Some(vals.fold((first_el, first_el), |(min_val, max_val), el| {
-            (min_val.min(el), max_val.max(el))
-        }));
+    let first_el = vals.find(|val| {
+        // We use this to make sure we skip all NaN values when
+        // working with a float type.
+        val.partial_cmp(val) == Some(Ordering::Equal)
+    })?;
+    let mut min_so_far: T = first_el;
+    let mut max_so_far: T = first_el;
+    for val in vals {
+        if val.partial_cmp(&min_so_far) == Some(Ordering::Less) {
+            min_so_far = val;
+        }
+        if val.partial_cmp(&max_so_far) == Some(Ordering::Greater) {
+            max_so_far = val;
+        }
     }
-    None
+    Some((min_so_far, max_so_far))
 }
 
-#[test]
-fn test_compute_num_bits() {
-    assert_eq!(compute_num_bits(1), 1u8);
-    assert_eq!(compute_num_bits(0), 0u8);
-    assert_eq!(compute_num_bits(2), 2u8);
-    assert_eq!(compute_num_bits(3), 2u8);
-    assert_eq!(compute_num_bits(4), 3u8);
-    assert_eq!(compute_num_bits(255), 8u8);
-    assert_eq!(compute_num_bits(256), 9u8);
-    assert_eq!(compute_num_bits(5_000_000_000), 33u8);
-}
+#[cfg(test)]
+mod tests {
+    use super::*;
 
-#[test]
-fn test_minmax_empty() {
-    let vals: Vec<u32> = vec![];
-    assert_eq!(minmax(vals.into_iter()), None);
-}
+    #[test]
+    fn test_compute_num_bits() {
+        assert_eq!(compute_num_bits(1), 1u8);
+        assert_eq!(compute_num_bits(0), 0u8);
+        assert_eq!(compute_num_bits(2), 2u8);
+        assert_eq!(compute_num_bits(3), 2u8);
+        assert_eq!(compute_num_bits(4), 3u8);
+        assert_eq!(compute_num_bits(255), 8u8);
+        assert_eq!(compute_num_bits(256), 9u8);
+        assert_eq!(compute_num_bits(5_000_000_000), 33u8);
+    }
 
-#[test]
-fn test_minmax_one() {
-    assert_eq!(minmax(vec![1].into_iter()), Some((1, 1)));
-}
+    #[test]
+    fn test_minmax_empty() {
+        let vals: Vec<u32> = vec![];
+        assert_eq!(minmax(vals.into_iter()), None);
+    }
 
-#[test]
-fn test_minmax_two() {
-    assert_eq!(minmax(vec![1, 2].into_iter()), Some((1, 2)));
-    assert_eq!(minmax(vec![2, 1].into_iter()), Some((1, 2)));
+    #[test]
+    fn test_minmax_one() {
+        assert_eq!(minmax(vec![1].into_iter()), Some((1, 1)));
+    }
+
+    #[test]
+    fn test_minmax_two() {
+        assert_eq!(minmax(vec![1, 2].into_iter()), Some((1, 2)));
+        assert_eq!(minmax(vec![2, 1].into_iter()), Some((1, 2)));
+    }
+
+    #[test]
+    fn test_minmax_nan() {
+        assert_eq!(
+            minmax(vec![f64::NAN, 1f64, 2f64].into_iter()),
+            Some((1f64, 2f64))
+        );
+        assert_eq!(
+            minmax(vec![2f64, f64::NAN, 1f64].into_iter()),
+            Some((1f64, 2f64))
+        );
+        assert_eq!(
+            minmax(vec![2f64, 1f64, f64::NAN].into_iter()),
+            Some((1f64, 2f64))
+        );
+    }
+
+    #[test]
+    fn test_minmax_inf() {
+        assert_eq!(
+            minmax(vec![f64::INFINITY, 1f64, 2f64].into_iter()),
+            Some((1f64, f64::INFINITY))
+        );
+        assert_eq!(
+            minmax(vec![-f64::INFINITY, 1f64, 2f64].into_iter()),
+            Some((-f64::INFINITY, 2f64))
+        );
+        assert_eq!(
+            minmax(vec![2f64, f64::INFINITY, 1f64].into_iter()),
+            Some((1f64, f64::INFINITY))
+        );
+        assert_eq!(
+            minmax(vec![2f64, 1f64, -f64::INFINITY].into_iter()),
+            Some((-f64::INFINITY, 2f64))
+        );
+    }
 }

columnar/Cargo.toml

@@ -2,25 +2,18 @@
 name = "tantivy-columnar"
 version = "0.1.0"
 edition = "2021"
+license = "MIT"
 
 [dependencies]
 stacker = { path = "../stacker", package="tantivy-stacker"}
 serde_json = "1"
 thiserror = "1"
 fnv = "1"
-tantivy-fst =  "0.4.0"
 sstable = { path = "../sstable", package = "tantivy-sstable" }
+zstd = "0.12"
 common = { path = "../common", package = "tantivy-common" }
 fastfield_codecs = { path = "../fastfield_codecs"}
-ordered-float = "3.4"
 itertools = "0.10"
 
-[features]
-# default = ["quickwit"]
-# quickwit = ["common/quickwit"]
-
-
-
-
 [dev-dependencies]
 proptest = "1"

columnar/README.md

@@ -2,7 +2,6 @@
 
 This crate describes columnar format used in tantivy.
 
-
 ## Goals
 
 This format is special in the following way.
@@ -15,14 +14,55 @@ we need to be able to load columns rapidly.
 and different cardinality `(required, optional, multivalued)`.
 - columns, once loaded, offer cheap random access.
 
-# Format
+# Coercion rules
 
-A quickwit/tantivy style sstable associated
-`(column names, column_cardinality, column_type) to range of bytes.
+Users can create a columnar by appending rows to a writer.
+Nothing prevents a user from recording values with different to a same `column_key`.
 
-The format of the key is:
+In that case, `tantivy-columnar`'s behavior is as follows:
+- Values that corresponds to different JsonValue type are mapped to different columns. For instance, String values are treated independently from Number or boolean values. `tantivy-columnar` will simply emit several columns associated to a given column_name.
+- Only one column for a given json value type is emitted.  If number values with different number types are recorded (e.g. u64, i64, f64), `tantivy-columnar` will pick the first type that can represents the set of appended value, with the following prioriy order (`i64`, `u64`, `f64`). `i64` is picked over `u64` as it is likely to  yield less change of types. Most use cases strictly requiring `u64` show the restriction on 50% of the values (e.g. a 64-bit hash). On the other hand, a lot of use cases can show rare negative value.
+
+# Columnar format
+
+Because this columnar format tries to avoid some coercion.
+There can be several columns (with different type) associated to a single `column_name`.
+
+Each column is associated to `column_key`.
+The format of that key is:
 `[column_name][ZERO_BYTE][column_type_header: u8]`
 
+```
+COLUMNAR:=
+    [COLUMNAR_DATA]
+    [COLUMNAR_INDEX]
+    [COLUMNAR_FOOTER];
+
+
+# Columns are sorted by their column key.
+COLUMNAR_DATA:=
+    [COLUMN]+;
+
+COLUMN:=
+    COMPRESSED_COLUMN | NON_COMPRESSED_COLUMN;
+
+# COLUMN_DATA is compressed when it exceeds a threshold of 100KB.
+
+COMPRESSED_COLUMN := [b'1'][zstd(COLUMN_DATA)]
+NON_COMPRESSED_COLUMN:= [b'0'][COLUMN_DATA]
+
+COLUMNAR_INDEX := [RANGE_SSTABLE_BYTES]
+
+COLUMNAR_FOOTER := [RANGE_SSTABLE_BYTES_LEN: 8 bytes little endian]
+
+```
+
+The columnar file starts by the actual column data, concatenated one after the other,
+sorted by column key.
+
+A quickwit/tantivy style sstable associates
+`(column names, column_cardinality, column_type) to range of bytes.
+
 Column name may not contain the zero byte.
 
 Listing all columns associated to `column_name` can therefore

columnar/columnar-cli/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "tantivy-columnar-cli"
+version = "0.1.0"
+edition = "2021"
+license = "MIT"
+
+[dependencies]
+columnar = {path="../", package="tantivy-columnar"}
+serde_json = "1"
+serde_json_borrow = {git="https://github.com/PSeitz/serde_json_borrow/"}
+serde = "1"
+
+[workspace]
+members = []
+
+[profile.release]
+debug = true

columnar/columnar-cli/src/main.rs

@@ -0,0 +1,126 @@
+use columnar::ColumnarWriter;
+use columnar::NumericalValue;
+use serde_json_borrow;
+use std::fs::File;
+use std::io;
+use std::io::BufRead;
+use std::io::BufReader;
+use std::time::Instant;
+
+#[derive(Default)]
+struct JsonStack {
+    path: String,
+    stack: Vec<usize>,
+}
+
+impl JsonStack {
+    fn push(&mut self, seg: &str) {
+        let len = self.path.len();
+        self.stack.push(len);
+        self.path.push('.');
+        self.path.push_str(seg);
+    }
+
+    fn pop(&mut self) {
+        if let Some(len) = self.stack.pop() {
+            self.path.truncate(len);
+        }
+    }
+
+    fn path(&self) -> &str {
+        &self.path[1..]
+    }
+}
+
+fn append_json_to_columnar(
+    doc: u32,
+    json_value: &serde_json_borrow::Value,
+    columnar: &mut ColumnarWriter,
+    stack: &mut JsonStack,
+) -> usize {
+    let mut count = 0;
+    match json_value {
+        serde_json_borrow::Value::Null => {}
+        serde_json_borrow::Value::Bool(val) => {
+            columnar.record_numerical(
+                doc,
+                stack.path(),
+                NumericalValue::from(if *val { 1u64 } else { 0u64 }),
+            );
+            count += 1;
+        }
+        serde_json_borrow::Value::Number(num) => {
+            let numerical_value: NumericalValue = if let Some(num_i64) = num.as_i64() {
+                num_i64.into()
+            } else if let Some(num_u64) = num.as_u64() {
+                num_u64.into()
+            } else if let Some(num_f64) = num.as_f64() {
+                num_f64.into()
+            } else {
+                panic!();
+            };
+            count += 1;
+            columnar.record_numerical(
+                doc,
+                stack.path(),
+                numerical_value,
+            );
+        }
+        serde_json_borrow::Value::Str(msg) => {
+            columnar.record_str(
+                doc,
+                stack.path(),
+                msg.as_bytes(),
+            );
+            count += 1;
+        },
+        serde_json_borrow::Value::Array(vals) => {
+            for val in vals {
+                count += append_json_to_columnar(doc, val, columnar, stack);
+            }
+        },
+        serde_json_borrow::Value::Object(json_map) => {
+            for (child_key, child_val) in json_map {
+                stack.push(child_key);
+                count += append_json_to_columnar(doc, child_val, columnar, stack);
+                stack.pop();
+            }
+        },
+    }
+    count
+}
+
+fn main() -> io::Result<()> {
+    let file = File::open("gh_small.json")?;
+    let mut reader = BufReader::new(file);
+    let mut line = String::with_capacity(100);
+    let mut columnar = columnar::ColumnarWriter::default();
+    let mut doc = 0;
+    let start = Instant::now();
+    let mut stack = JsonStack::default();
+    let mut total_count = 0;
+    loop {
+        line.clear();
+        let len = reader.read_line(&mut line)?;
+        if len == 0 {
+            break;
+        }
+        let Ok(json_value) = serde_json::from_str::<serde_json_borrow::Value>(&line) else { continue; };
+        total_count += append_json_to_columnar(doc, &json_value, &mut columnar, &mut stack);
+        doc += 1;
+    }
+    println!("value count {total_count}");
+    println!("record {:?}", start.elapsed());
+    let mut buffer = Vec::new();
+    columnar.serialize(doc, &mut buffer)?;
+    println!("num docs: {doc}, {:?}", start.elapsed());
+    println!("buffer len {} MB", buffer.len() / 1_000_000);
+    let columnar = columnar::ColumnarReader::open(buffer)?;
+    for (column_name, typ, offsets, num_bytes) in columnar.list_columns()? {
+        if num_bytes>1_000_000 {
+            println!("{column_name} {typ:?} {offsets:?} {}", num_bytes / 1_000_000);
+        }
+    }
+    println!("{} columns", columnar.num_columns());
+    Ok(())
+}

columnar/src/column_type_header.rs

@@ -1,20 +1,26 @@
+use crate::utils::{place_bits, select_bits};
 use crate::value::NumericalType;
 
+/// Enum describing the number of values that can exist per document
+/// (or per row if you will).
 #[derive(Clone, Copy, Hash, Default, Debug, PartialEq, Eq, PartialOrd, Ord)]
 #[repr(u8)]
 pub enum Cardinality {
+    /// All documents contain exactly one value.
     #[default]
     Required = 0,
+    /// All documents contain at most one value.
     Optional = 1,
+    /// All documents may contain any number of values.
     Multivalued = 2,
 }
 
 impl Cardinality {
-    pub fn to_code(self) -> u8 {
+    pub(crate) fn to_code(self) -> u8 {
         self as u8
     }
 
-    pub fn try_from_code(code: u8) -> Option<Cardinality> {
+    pub(crate) fn try_from_code(code: u8) -> Option<Cardinality> {
         match code {
             0 => Some(Cardinality::Required),
             1 => Some(Cardinality::Optional),
@@ -28,25 +34,80 @@ impl Cardinality {
 pub enum ColumnType {
     Bytes,
     Numerical(NumericalType),
+    Bool,
 }
 
 impl ColumnType {
-    pub fn to_code(self) -> u8 {
+    /// Encoded over 6 bits.
+    pub(crate) fn to_code(self) -> u8 {
+        let high_type;
+        let low_code: u8;
         match self {
-            ColumnType::Bytes => 0u8,
-            ColumnType::Numerical(numerical_type) => 1u8 | (numerical_type.to_code() << 1),
+            ColumnType::Bytes => {
+                high_type = GeneralType::Str;
+                low_code = 0u8;
+            }
+            ColumnType::Numerical(numerical_type) => {
+                high_type = GeneralType::Numerical;
+                low_code = numerical_type.to_code();
+            }
+            ColumnType::Bool => {
+                high_type = GeneralType::Bool;
+                low_code = 0u8;
+            }
         }
+        place_bits::<3, 6>(high_type.to_code()) | place_bits::<0, 3>(low_code)
     }
 
-    pub fn try_from_code(code: u8) -> Option<ColumnType> {
-        if code == 0u8 {
-            return Some(ColumnType::Bytes);
-        }
-        if code & 1u8 == 0u8 {
+    pub(crate) fn try_from_code(code: u8) -> Option<ColumnType> {
+        if select_bits::<6, 8>(code) != 0u8 {
             return None;
         }
-        let numerical_type = NumericalType::try_from_code(code >> 1)?;
-        Some(ColumnType::Numerical(numerical_type))
+        let high_code = select_bits::<3, 6>(code);
+        let low_code = select_bits::<0, 3>(code);
+        let high_type = GeneralType::try_from_code(high_code)?;
+        match high_type {
+            GeneralType::Bool => {
+                if low_code != 0u8 {
+                    return None;
+                }
+                Some(ColumnType::Bool)
+            }
+            GeneralType::Str => {
+                if low_code != 0u8 {
+                    return None;
+                }
+                Some(ColumnType::Bytes)
+            }
+            GeneralType::Numerical => {
+                let numerical_type = NumericalType::try_from_code(low_code)?;
+                Some(ColumnType::Numerical(numerical_type))
+            }
+        }
+    }
+}
+
+/// This corresponds to the JsonType.
+#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug)]
+#[repr(u8)]
+pub(crate) enum GeneralType {
+    Bool = 0u8,
+    Str = 1u8,
+    Numerical = 2u8,
+}
+
+impl GeneralType {
+    pub fn to_code(self) -> u8 {
+        self as u8
+    }
+
+    pub fn try_from_code(code: u8) -> Option<Self> {
+        match code {
+            0u8 => Some(Self::Bool),
+            1u8 => Some(Self::Str),
+            2u8 => Some(Self::Numerical),
+            _ => None,
+        }
     }
 }
 
@@ -62,34 +123,6 @@ pub struct ColumnTypeAndCardinality {
     pub typ: ColumnType,
 }
 
-#[inline]
-const fn compute_mask(num_bits: u8) -> u8 {
-    if num_bits == 8 {
-        u8::MAX
-    } else {
-        (1u8 << num_bits) - 1
-    }
-}
-
-#[inline]
-fn select_bits<const START: u8, const END: u8>(code: u8) -> u8 {
-    assert!(START <= END);
-    assert!(END <= 8);
-    let num_bits: u8 = END - START;
-    let mask: u8 = compute_mask(num_bits);
-    (code >> START) & mask
-}
-
-#[inline]
-fn place_bits<const START: u8, const END: u8>(code: u8) -> u8 {
-    assert!(START <= END);
-    assert!(END <= 8);
-    let num_bits: u8 = END - START;
-    let mask: u8 = compute_mask(num_bits);
-    assert!(code <= mask);
-    code << START
-}
-
 impl ColumnTypeAndCardinality {
     pub fn to_code(self) -> u8 {
         place_bits::<6, 8>(self.cardinality.to_code()) | place_bits::<0, 6>(self.typ.to_code())
@@ -123,7 +156,8 @@ mod tests {
         }
         assert_eq!(
             column_type_header_set.len(),
-            3 /* cardinality */ * (1 + 3) // column_types
+            3 /* cardinality */ *
+            (1 + 1 + 3) // column_types (str, bool, numerical x 3)
         );
     }
 
@@ -136,7 +170,7 @@ mod tests {
                 assert!(column_type_set.insert(column_type));
             }
         }
-        assert_eq!(column_type_set.len(), 1 + 3);
+        assert_eq!(column_type_set.len(), 2 + 3);
     }
 
     #[test]

columnar/src/dictionary.rs

@@ -1,16 +1,27 @@
 use std::io;
 
 use fnv::FnvHashMap;
+use sstable::SSTable;
 
-fn fst_err_into_io_err(fst_err: tantivy_fst::Error) -> io::Error {
-    match fst_err {
-        tantivy_fst::Error::Fst(fst_err) => {
-            io::Error::new(io::ErrorKind::Other, format!("FST Error: {:?}", fst_err))
-        }
-        tantivy_fst::Error::Io(io_err) => io_err,
+pub(crate) struct IdMapping {
+    unordered_to_ord: Vec<OrderedId>,
+}
+
+impl IdMapping {
+    pub fn to_ord(&self, unordered: UnorderedId) -> OrderedId {
+        self.unordered_to_ord[unordered.0 as usize]
     }
 }
 
+/// When we add values, we cannot know their ordered id yet.
+/// For this reason, we temporarily assign them a `UnorderedId`
+/// that will be mapped to an `OrderedId` upon serialization.
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
+pub struct UnorderedId(pub u32);
+
+#[derive(Clone, Copy, Hash, PartialEq, Eq, Debug)]
+pub struct OrderedId(pub u32);
+
 /// `DictionaryBuilder` for dictionary encoding.
 ///
 /// It stores the different terms encounterred and assigns them a temporary value
@@ -19,20 +30,10 @@ fn fst_err_into_io_err(fst_err: tantivy_fst::Error) -> io::Error {
 /// Upon serialization, we will sort the ids and hence build a `UnorderedId -> Term ordinal`
 /// mapping.
 #[derive(Default)]
-pub struct DictionaryBuilder {
+pub(crate) struct DictionaryBuilder {
     dict: FnvHashMap<Vec<u8>, UnorderedId>,
 }
 
-pub struct IdMapping {
-    unordered_to_ord: Vec<OrderedId>,
-}
-
-impl IdMapping {
-    pub fn to_ord(&self, unordered: UnorderedId) -> OrderedId {
-        self.unordered_to_ord[unordered.0 as usize]
-    }
-}
-
 impl DictionaryBuilder {
     /// Get or allocate an unordered id.
     /// (This ID is simply an auto-incremented id.)
@@ -48,31 +49,36 @@ impl DictionaryBuilder {
     /// 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<IdMapping> {
-        serialize_inner(&self.dict, wrt).map_err(fst_err_into_io_err)
+        let mut terms: Vec<(&[u8], UnorderedId)> =
+            self.dict.iter().map(|(k, v)| (k.as_slice(), *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()];
+        let mut sstable_builder = sstable::VoidSSTable::writer(wrt);
+        for (ord, (key, unordered_id)) in terms.into_iter().enumerate() {
+            let ordered_id = OrderedId(ord as u32);
+            sstable_builder.insert(key, &())?;
+            unordered_to_ord[unordered_id.0 as usize] = ordered_id;
+        }
+        sstable_builder.finish()?;
+        Ok(IdMapping { unordered_to_ord })
     }
 }
 
-/// Helper function just there for error conversion.
-fn serialize_inner<'a, W: io::Write + 'a>(
-    dict: &FnvHashMap<Vec<u8>, UnorderedId>,
-    wrt: &mut W,
-) -> tantivy_fst::Result<IdMapping> {
-    let mut terms: Vec<(&[u8], UnorderedId)> =
-        dict.iter().map(|(k, v)| (k.as_slice(), *v)).collect();
-    terms.sort_unstable_by_key(|(key, _)| *key);
-    let mut unordered_to_ord: Vec<OrderedId> = vec![OrderedId(0u32); terms.len()];
-    let mut fst_builder = tantivy_fst::MapBuilder::new(wrt)?;
-    for (ord, (key, unordered_id)) in terms.into_iter().enumerate() {
-        let ordered_id = OrderedId(ord as u32);
-        fst_builder.insert(key, ord as u64)?;
-        unordered_to_ord[unordered_id.0 as usize] = ordered_id;
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_dictionary_builder() {
+        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 mut buffer = Vec::new();
+        let id_mapping = dictionary_builder.serialize(&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));
     }
-    fst_builder.finish()?;
-    Ok(IdMapping { unordered_to_ord })
 }
-
-#[derive(Clone, Copy, Debug)]
-pub struct UnorderedId(pub u32);
-
-#[derive(Clone, Copy)]
-pub struct OrderedId(pub u32);

columnar/src/lib.rs

@@ -1,32 +1,13 @@
-// Copyright (C) 2022 Quickwit, Inc.
-//
-// Quickwit is offered under the AGPL v3.0 and as commercial software.
-// For commercial licensing, contact us at hello@quickwit.io.
-//
-// AGPL:
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Affero General Public License as
-// published by the Free Software Foundation, either version 3 of the
-// License, or (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU Affero General Public License for more details.
-//
-// You should have received a copy of the GNU Affero General Public License
-// along with this program. If not, see <http://www.gnu.org/licenses/>.
-
 mod column_type_header;
 mod dictionary;
 mod reader;
-mod serializer;
+pub(crate) mod utils;
 mod value;
 mod writer;
 
 pub use column_type_header::Cardinality;
 pub use reader::ColumnarReader;
-pub use serializer::ColumnarSerializer;
+pub use value::{NumericalType, NumericalValue};
 pub use writer::ColumnarWriter;
 
 pub type DocId = u32;
@@ -37,21 +18,57 @@ mod tests {
 
     use common::file_slice::FileSlice;
 
-    use crate::column_type_header::ColumnTypeAndCardinality;
+    use crate::column_type_header::{ColumnType, ColumnTypeAndCardinality};
     use crate::reader::ColumnarReader;
-    use crate::serializer::ColumnarSerializer;
     use crate::value::NumericalValue;
-    use crate::ColumnarWriter;
+    use crate::{Cardinality, ColumnarWriter};
 
     #[test]
-    fn test_dataframe_writer() {
+    fn test_dataframe_writer_bytes() {
         let mut dataframe_writer = ColumnarWriter::default();
-        dataframe_writer.record_numerical(1u32, b"srical.value", NumericalValue::U64(1u64));
-        dataframe_writer.record_numerical(2u32, b"srical.value", NumericalValue::U64(2u64));
-        dataframe_writer.record_numerical(4u32, b"srical.value", NumericalValue::I64(2i64));
+        dataframe_writer.record_str(1u32, "my_string", b"hello");
+        dataframe_writer.record_str(3u32, "my_string", b"helloeee");
         let mut buffer: Vec<u8> = Vec::new();
-        let serializer = ColumnarSerializer::new(&mut buffer);
-        dataframe_writer.serialize(5, serializer).unwrap();
+        dataframe_writer.serialize(5, &mut buffer).unwrap();
+        let columnar_fileslice = FileSlice::from(buffer);
+        let columnar = ColumnarReader::open(columnar_fileslice).unwrap();
+        assert_eq!(columnar.num_columns(), 1);
+        let cols: Vec<(ColumnTypeAndCardinality, Range<u64>)> =
+            columnar.read_columns("my_string").unwrap();
+        assert_eq!(cols.len(), 1);
+        assert_eq!(cols[0].1, 0..159);
+    }
+
+    #[test]
+    fn test_dataframe_writer_bool() {
+        let mut dataframe_writer = ColumnarWriter::default();
+        dataframe_writer.record_bool(1u32, "bool.value", false);
+        let mut buffer: Vec<u8> = Vec::new();
+        dataframe_writer.serialize(5, &mut buffer).unwrap();
+        let columnar_fileslice = FileSlice::from(buffer);
+        let columnar = ColumnarReader::open(columnar_fileslice).unwrap();
+        assert_eq!(columnar.num_columns(), 1);
+        let cols: Vec<(ColumnTypeAndCardinality, Range<u64>)> =
+            columnar.read_columns("bool.value").unwrap();
+        assert_eq!(cols.len(), 1);
+        assert_eq!(
+            cols[0].0,
+            ColumnTypeAndCardinality {
+                cardinality: Cardinality::Optional,
+                typ: ColumnType::Bool
+            }
+        );
+        assert_eq!(cols[0].1, 0..22);
+    }
+
+    #[test]
+    fn test_dataframe_writer_numerical() {
+        let mut dataframe_writer = ColumnarWriter::default();
+        dataframe_writer.record_numerical(1u32, "srical.value", NumericalValue::U64(12u64));
+        dataframe_writer.record_numerical(2u32, "srical.value", NumericalValue::U64(13u64));
+        dataframe_writer.record_numerical(4u32, "srical.value", NumericalValue::U64(15u64));
+        let mut buffer: Vec<u8> = Vec::new();
+        dataframe_writer.serialize(5, &mut buffer).unwrap();
         let columnar_fileslice = FileSlice::from(buffer);
         let columnar = ColumnarReader::open(columnar_fileslice).unwrap();
         assert_eq!(columnar.num_columns(), 1);
@@ -64,6 +81,6 @@ mod tests {
         // - vals  8 //< due to padding? could have been 1byte?.
         // - null footer 6 bytes
         // - version footer 3 bytes // Should be file-wide
-        assert_eq!(cols[0].1, 0..31);
+        assert_eq!(cols[0].1, 0..32);
     }
 }

columnar/src/reader/mod.rs

@@ -3,7 +3,7 @@ use std::{io, mem};
 
 use common::file_slice::FileSlice;
 use common::BinarySerializable;
-use sstable::{Dictionary, SSTableRange};
+use sstable::{Dictionary, RangeSSTable};
 
 use crate::column_type_header::ColumnTypeAndCardinality;
 
@@ -11,17 +11,22 @@ fn io_invalid_data(msg: String) -> io::Error {
     io::Error::new(io::ErrorKind::InvalidData, msg) // format!("Invalid key found.
                                                     // {key_bytes:?}")));
 }
+
+/// The ColumnarReader makes it possible to access a set of columns
+/// associated to field names.
 pub struct ColumnarReader {
-    column_dictionary: Dictionary<SSTableRange>,
+    column_dictionary: Dictionary<RangeSSTable>,
     column_data: FileSlice,
 }
 
 impl ColumnarReader {
-    pub fn num_columns(&self) -> usize {
-        self.column_dictionary.num_terms()
+    /// Opens a new Columnar file.
+    pub fn open<F>(file_slice: F) -> io::Result<ColumnarReader>
+    where FileSlice: From<F> {
+        Self::open_inner(file_slice.into())
     }
 
-    pub fn open(file_slice: FileSlice) -> io::Result<ColumnarReader> {
+    fn open_inner(file_slice: FileSlice) -> io::Result<ColumnarReader> {
         let (file_slice_without_sstable_len, sstable_len_bytes) =
             file_slice.split_from_end(mem::size_of::<u64>());
         let mut sstable_len_bytes = sstable_len_bytes.read_bytes()?;
@@ -35,6 +40,32 @@ impl ColumnarReader {
         })
     }
 
+    // TODO fix ugly API
+    pub fn list_columns(
+        &self,
+    ) -> io::Result<Vec<(String, ColumnTypeAndCardinality, Range<u64>, u64)>> {
+        let mut stream = self.column_dictionary.stream()?;
+        let mut results = Vec::new();
+        while stream.advance() {
+            let key_bytes: &[u8] = stream.key();
+            let column_code: u8 = key_bytes.last().cloned().unwrap();
+            let column_type_and_cardinality = ColumnTypeAndCardinality::try_from_code(column_code)
+                .ok_or_else(|| io_invalid_data(format!("Unknown column code `{column_code}`")))?;
+            let range = stream.value().clone();
+            let column_name = String::from_utf8_lossy(&key_bytes[..key_bytes.len() - 1]);
+            let range_len = range.end - range.start;
+            results.push((
+                column_name.to_string(),
+                column_type_and_cardinality,
+                range,
+                range_len,
+            ));
+        }
+        Ok(results)
+    }
+
+    /// Get all columns for the given field_name.
+    // TODO fix ugly API
     pub fn read_columns(
         &self,
         field_name: &str,
@@ -63,4 +94,9 @@ impl ColumnarReader {
         }
         Ok(results)
     }
+
+    /// Return the number of columns in the columnar.
+    pub fn num_columns(&self) -> usize {
+        self.column_dictionary.num_terms()
+    }
 }

columnar/src/serializer.rs

@@ -1,39 +0,0 @@
-use std::io;
-use std::io::Write;
-use std::ops::Range;
-
-use common::CountingWriter;
-use sstable::value::RangeWriter;
-use sstable::SSTableRange;
-
-pub struct ColumnarSerializer<W: io::Write> {
-    wrt: CountingWriter<W>,
-    sstable_range: sstable::Writer<Vec<u8>, RangeWriter>,
-}
-
-impl<W: io::Write> ColumnarSerializer<W> {
-    pub fn new(wrt: W) -> ColumnarSerializer<W> {
-        let sstable_range: sstable::Writer<Vec<u8>, RangeWriter> =
-            sstable::Dictionary::<SSTableRange>::builder(Vec::with_capacity(100_000)).unwrap();
-        ColumnarSerializer {
-            wrt: CountingWriter::wrap(wrt),
-            sstable_range,
-        }
-    }
-
-    pub fn record_column_offsets(&mut self, key: &[u8], byte_range: Range<u64>) -> io::Result<()> {
-        self.sstable_range.insert(key, &byte_range)
-    }
-
-    pub fn wrt(&mut self) -> &mut CountingWriter<W> {
-        &mut self.wrt
-    }
-
-    pub fn finalize(mut self) -> io::Result<()> {
-        let sstable_bytes: Vec<u8> = self.sstable_range.finish()?;
-        let sstable_num_bytes: u64 = sstable_bytes.len() as u64;
-        self.wrt.write_all(&sstable_bytes)?;
-        self.wrt.write_all(&sstable_num_bytes.to_le_bytes()[..])?;
-        Ok(())
-    }
-}

columnar/src/utils.rs

@@ -0,0 +1,76 @@
+const fn compute_mask(num_bits: u8) -> u8 {
+    if num_bits == 8 {
+        u8::MAX
+    } else {
+        (1u8 << num_bits) - 1
+    }
+}
+
+#[inline(always)]
+#[must_use]
+pub(crate) fn select_bits<const START: u8, const END: u8>(code: u8) -> u8 {
+    assert!(START <= END);
+    assert!(END <= 8);
+    let num_bits: u8 = END - START;
+    let mask: u8 = compute_mask(num_bits);
+    (code >> START) & mask
+}
+
+#[inline(always)]
+#[must_use]
+pub(crate) fn place_bits<const START: u8, const END: u8>(code: u8) -> u8 {
+    assert!(START <= END);
+    assert!(END <= 8);
+    let num_bits: u8 = END - START;
+    let mask: u8 = compute_mask(num_bits);
+    assert!(code <= mask);
+    code << START
+}
+
+/// Pop-front one bytes from a slice of bytes.
+#[inline(always)]
+pub fn pop_first_byte(bytes: &mut &[u8]) -> Option<u8> {
+    if bytes.is_empty() {
+        return None;
+    }
+    let first_byte = bytes[0];
+    *bytes = &bytes[1..];
+    Some(first_byte)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_select_bits() {
+        assert_eq!(255u8, select_bits::<0, 8>(255u8));
+        assert_eq!(0u8, select_bits::<0, 0>(255u8));
+        assert_eq!(8u8, select_bits::<0, 4>(8u8));
+        assert_eq!(4u8, select_bits::<1, 4>(8u8));
+        assert_eq!(0u8, select_bits::<1, 3>(8u8));
+    }
+
+    #[test]
+    fn test_place_bits() {
+        assert_eq!(255u8, place_bits::<0, 8>(255u8));
+        assert_eq!(4u8, place_bits::<2, 3>(1u8));
+        assert_eq!(0u8, place_bits::<2, 2>(0u8));
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_place_bits_overflows() {
+        let _ = place_bits::<1, 4>(8u8);
+    }
+
+    #[test]
+    fn test_pop_first_byte() {
+        let mut cursor: &[u8] = &b"abcd"[..];
+        assert_eq!(pop_first_byte(&mut cursor), Some(b'a'));
+        assert_eq!(pop_first_byte(&mut cursor), Some(b'b'));
+        assert_eq!(pop_first_byte(&mut cursor), Some(b'c'));
+        assert_eq!(pop_first_byte(&mut cursor), Some(b'd'));
+        assert_eq!(pop_first_byte(&mut cursor), None);
+    }
+}

columnar/src/value.rs

@@ -1,10 +1,8 @@
-use ordered_float::NotNan;
-
 #[derive(Copy, Clone, Debug, PartialEq)]
 pub enum NumericalValue {
     I64(i64),
     U64(u64),
-    F64(NotNan<f64>),
+    F64(f64),
 }
 
 impl From<u64> for NumericalValue {
@@ -19,8 +17,8 @@ impl From<i64> for NumericalValue {
     }
 }
 
-impl From<NotNan<f64>> for NumericalValue {
-    fn from(val: NotNan<f64>) -> Self {
+impl From<f64> for NumericalValue {
+    fn from(val: f64) -> Self {
         NumericalValue::F64(val)
     }
 }
@@ -95,11 +93,11 @@ impl Coerce for u64 {
     }
 }
 
-impl Coerce for NotNan<f64> {
+impl Coerce for f64 {
     fn coerce(value: NumericalValue) -> Self {
         match value {
-            NumericalValue::I64(val) => unsafe { NotNan::new_unchecked(val as f64) },
-            NumericalValue::U64(val) => unsafe { NotNan::new_unchecked(val as f64) },
+            NumericalValue::I64(val) => val as f64,
+            NumericalValue::U64(val) => val as f64,
             NumericalValue::F64(val) => val,
         }
     }

columnar/src/writer/column_operation.rs

@@ -1,12 +1,7 @@
-use std::fmt;
-use std::num::NonZeroU8;
-
-use ordered_float::NotNan;
-use thiserror::Error;
-
 use crate::dictionary::UnorderedId;
+use crate::utils::{place_bits, pop_first_byte, select_bits};
 use crate::value::NumericalValue;
-use crate::DocId;
+use crate::{DocId, NumericalType};
 
 /// When we build a columnar dataframe, we first just group
 /// all mutations per column, and append them in append-only object.
@@ -18,6 +13,76 @@ pub(crate) enum ColumnOperation<T> {
     Value(T),
 }
 
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+struct ColumnOperationHeader {
+    typ_code: u8,
+    len: u8,
+}
+
+impl ColumnOperationHeader {
+    fn to_code(self) -> u8 {
+        place_bits::<0, 4>(self.len) | place_bits::<4, 8>(self.typ_code)
+    }
+
+    fn from_code(code: u8) -> Self {
+        let len = select_bits::<0, 4>(code);
+        let typ_code = select_bits::<4, 8>(code);
+        ColumnOperationHeader { typ_code, len }
+    }
+}
+
+const NEW_DOC_CODE: u8 = 0u8;
+const NEW_VALUE_CODE: u8 = 1u8;
+
+impl<V: SymbolValue> ColumnOperation<V> {
+    pub fn serialize(self) -> impl AsRef<[u8]> {
+        let mut minibuf = MiniBuffer::default();
+        let header = match self {
+            ColumnOperation::NewDoc(new_doc) => {
+                let symbol_len = new_doc.serialize(&mut minibuf.bytes[1..]);
+                ColumnOperationHeader {
+                    typ_code: NEW_DOC_CODE,
+                    len: symbol_len,
+                }
+            }
+            ColumnOperation::Value(val) => {
+                let symbol_len = val.serialize(&mut minibuf.bytes[1..]);
+                ColumnOperationHeader {
+                    typ_code: NEW_VALUE_CODE,
+                    len: symbol_len,
+                }
+            }
+        };
+        minibuf.bytes[0] = header.to_code();
+        minibuf.len = 1 + header.len;
+        minibuf
+    }
+
+    /// Deserialize a colummn operation.
+    /// Returns None if the buffer is empty.
+    ///
+    /// Panics if the payload is invalid.
+    pub fn deserialize(bytes: &mut &[u8]) -> Option<Self> {
+        let header_byte = pop_first_byte(bytes)?;
+        let column_op_header = ColumnOperationHeader::from_code(header_byte);
+        let symbol_bytes: &[u8];
+        (symbol_bytes, *bytes) = bytes.split_at(column_op_header.len as usize);
+        match column_op_header.typ_code {
+            NEW_DOC_CODE => {
+                let new_doc = u32::deserialize(symbol_bytes);
+                Some(ColumnOperation::NewDoc(new_doc))
+            }
+            NEW_VALUE_CODE => {
+                let value = V::deserialize(symbol_bytes);
+                Some(ColumnOperation::Value(value))
+            }
+            _ => {
+                panic!("Unknown code {}", column_op_header.typ_code);
+            }
+        }
+    }
+}
+
 impl<T> From<T> for ColumnOperation<T> {
     fn from(value: T) -> Self {
         ColumnOperation::Value(value)
@@ -25,207 +90,116 @@ impl<T> From<T> for ColumnOperation<T> {
 }
 
 #[allow(clippy::from_over_into)]
-pub(crate) trait SymbolValue: Into<MiniBuffer> + Clone + Copy + fmt::Debug {
-    fn deserialize(header: NonZeroU8, bytes: &mut &[u8]) -> Result<Self, ParseError>;
+pub(crate) trait SymbolValue: Clone + Copy {
+    fn serialize(self, buffer: &mut [u8]) -> u8;
+
+    // Reads the header type and the given bytes.
+    //
+    // `bytes` does not contain the header byte.
+    // This method should advance bytes by the number of bytes that were consumed.
+    fn deserialize(bytes: &[u8]) -> Self;
 }
 
-pub(crate) struct MiniBuffer {
-    pub bytes: [u8; 9],
-    pub len: usize,
-}
+impl SymbolValue for bool {
+    fn serialize(self, buffer: &mut [u8]) -> u8 {
+        buffer[0] = if self { 1u8 } else { 0u8 };
+        1u8
+    }
 
-impl MiniBuffer {
-    pub fn as_slice(&self) -> &[u8] {
-        &self.bytes[..self.len]
+    fn deserialize(bytes: &[u8]) -> Self {
+        bytes[0] == 1u8
     }
 }
 
-fn compute_header_byte(typ: SymbolType, len: usize) -> u8 {
-    assert!(len <= 9);
-    (len << 4) as u8 | typ as u8
+#[derive(Default)]
+struct MiniBuffer {
+    pub bytes: [u8; 10],
+    pub len: u8,
+}
+
+impl AsRef<[u8]> for MiniBuffer {
+    fn as_ref(&self) -> &[u8] {
+        &self.bytes[..self.len as usize]
+    }
 }
 
 impl SymbolValue for NumericalValue {
-    fn deserialize(header_byte: NonZeroU8, bytes: &mut &[u8]) -> Result<Self, ParseError> {
-        let (typ, len) = parse_header_byte(header_byte)?;
-        let value_bytes: &[u8];
-        (value_bytes, *bytes) = bytes.split_at(len);
-        let symbol: NumericalValue = match typ {
-            SymbolType::U64 => {
-                let mut octet: [u8; 8] = [0u8; 8];
-                octet[..value_bytes.len()].copy_from_slice(value_bytes);
+    fn deserialize(mut bytes: &[u8]) -> Self {
+        let type_code = pop_first_byte(&mut bytes).unwrap();
+        let symbol_type = NumericalType::try_from_code(type_code).unwrap();
+        let mut octet: [u8; 8] = [0u8; 8];
+        octet[..bytes.len()].copy_from_slice(bytes);
+        match symbol_type {
+            NumericalType::U64 => {
                 let val: u64 = u64::from_le_bytes(octet);
                 NumericalValue::U64(val)
             }
-            SymbolType::I64 => {
-                let mut octet: [u8; 8] = [0u8; 8];
-                octet[..value_bytes.len()].copy_from_slice(value_bytes);
+            NumericalType::I64 => {
                 let encoded: u64 = u64::from_le_bytes(octet);
                 let val: i64 = decode_zig_zag(encoded);
                 NumericalValue::I64(val)
             }
-            SymbolType::Float => {
-                let octet: [u8; 8] =
-                    value_bytes.try_into().map_err(|_| ParseError::InvalidLen {
-                        typ: SymbolType::Float,
-                        len,
-                    })?;
-                let val_possibly_nan = f64::from_le_bytes(octet);
-                let val_not_nan = NotNan::new(val_possibly_nan)
-                    .map_err(|_| ParseError::NaN)?;
-                NumericalValue::F64(val_not_nan)
+            NumericalType::F64 => {
+                debug_assert_eq!(bytes.len(), 8);
+                let val: f64 = f64::from_le_bytes(octet);
+                NumericalValue::F64(val)
             }
-        };
-        Ok(symbol)
+        }
     }
-}
 
-#[allow(clippy::from_over_into)]
-impl Into<MiniBuffer> for NumericalValue {
-    fn into(self) -> MiniBuffer {
-        let mut bytes = [0u8; 9];
+    fn serialize(self, output: &mut [u8]) -> u8 {
         match self {
             NumericalValue::F64(val) => {
-                let len = 8;
-                let header_byte = compute_header_byte(SymbolType::Float, len);
-                bytes[0] = header_byte;
-                bytes[1..].copy_from_slice(&val.to_le_bytes());
-                MiniBuffer {
-                    bytes,
-                    len: len + 1,
-                }
+                output[0] = NumericalType::F64 as u8;
+                output[1..9].copy_from_slice(&val.to_le_bytes());
+                9u8
             }
             NumericalValue::U64(val) => {
-                let len = compute_num_bytes_for_u64(val);
-                let header_byte = compute_header_byte(SymbolType::U64, len);
-                bytes[0] = header_byte;
-                bytes[1..].copy_from_slice(&val.to_le_bytes());
-                MiniBuffer {
-                    bytes,
-                    len: len + 1,
-                }
+                let len = compute_num_bytes_for_u64(val) as u8;
+                output[0] = NumericalType::U64 as u8;
+                output[1..9].copy_from_slice(&val.to_le_bytes());
+                len + 1u8
             }
             NumericalValue::I64(val) => {
-                let encoded = encode_zig_zag(val);
-                let len = compute_num_bytes_for_u64(encoded);
-                let header_byte = compute_header_byte(SymbolType::I64, len);
-                bytes[0] = header_byte;
-                bytes[1..].copy_from_slice(&encoded.to_le_bytes());
-                MiniBuffer {
-                    bytes,
-                    len: len + 1,
-                }
+                let zig_zag_encoded = encode_zig_zag(val);
+                let len = compute_num_bytes_for_u64(zig_zag_encoded) as u8;
+                output[0] = NumericalType::I64 as u8;
+                output[1..9].copy_from_slice(&zig_zag_encoded.to_le_bytes());
+                len + 1u8
             }
         }
     }
 }
 
-#[allow(clippy::from_over_into)]
-impl Into<MiniBuffer> for UnorderedId {
-    fn into(self) -> MiniBuffer {
-        let mut bytes = [0u8; 9];
-        let val = self.0 as u64;
-        let len = compute_num_bytes_for_u64(val) + 1;
-        bytes[0] = len as u8;
-        bytes[1..].copy_from_slice(&val.to_le_bytes());
-        MiniBuffer { bytes, len }
+impl SymbolValue for u32 {
+    fn serialize(self, output: &mut [u8]) -> u8 {
+        let len = compute_num_bytes_for_u64(self as u64);
+        output[0..4].copy_from_slice(&self.to_le_bytes());
+        len as u8
+    }
+
+    fn deserialize(bytes: &[u8]) -> Self {
+        let mut quartet: [u8; 4] = [0u8; 4];
+        quartet[..bytes.len()].copy_from_slice(bytes);
+        u32::from_le_bytes(quartet)
     }
 }
 
 impl SymbolValue for UnorderedId {
-    fn deserialize(header: NonZeroU8, bytes: &mut &[u8]) -> Result<UnorderedId, ParseError> {
-        let len = header.get() as usize;
-        let symbol_bytes: &[u8];
-        (symbol_bytes, *bytes) = bytes.split_at(len);
-        let mut value_bytes = [0u8; 4];
-        value_bytes[..len - 1].copy_from_slice(&symbol_bytes[1..]);
-        let value = u32::from_le_bytes(value_bytes);
-        Ok(UnorderedId(value))
+    fn serialize(self, output: &mut [u8]) -> u8 {
+        self.0.serialize(output)
+    }
+
+    fn deserialize(bytes: &[u8]) -> Self {
+        UnorderedId(u32::deserialize(bytes))
     }
 }
 
-const HEADER_MASK: u8 = (1u8 << 4) - 1u8;
-
 fn compute_num_bytes_for_u64(val: u64) -> usize {
     let msb = (64u32 - val.leading_zeros()) as usize;
     (msb + 7) / 8
 }
 
-fn parse_header_byte(byte: NonZeroU8) -> Result<(SymbolType, usize), ParseError> {
-    let len = (byte.get() as usize) >> 4;
-    let typ_code = byte.get() & HEADER_MASK;
-    let typ = SymbolType::try_from(typ_code)?;
-    Ok((typ, len))
-}
-
-#[derive(Error, Debug)]
-pub enum ParseError {
-    #[error("Type byte unknown `{0}`")]
-    UnknownType(u8),
-    #[error("Invalid len for type `{len}` for type `{typ:?}`.")]
-    InvalidLen { typ: SymbolType, len: usize },
-    #[error("Missing bytes.")]
-    MissingBytes,
-    #[error("Not a number value.")]
-    NaN,
-}
-
-impl<V: SymbolValue> ColumnOperation<V> {
-    pub fn serialize(self) -> MiniBuffer {
-        match self {
-            ColumnOperation::NewDoc(doc) => {
-                let mut minibuf: [u8; 9] = [0u8; 9];
-                minibuf[0] = 0u8;
-                minibuf[1..5].copy_from_slice(&doc.to_le_bytes());
-                MiniBuffer {
-                    bytes: minibuf,
-                    len: 5,
-                }
-            }
-            ColumnOperation::Value(val) => val.into(),
-        }
-    }
-
-    pub fn deserialize(bytes: &mut &[u8]) -> Result<Self, ParseError> {
-        if bytes.is_empty() {
-            return Err(ParseError::MissingBytes);
-        }
-        let header_byte = bytes[0];
-        *bytes = &bytes[1..];
-        if let Some(header_byte) = NonZeroU8::new(header_byte) {
-            let value = V::deserialize(header_byte, bytes)?;
-            Ok(ColumnOperation::Value(value))
-        } else {
-            let doc_bytes: &[u8];
-            (doc_bytes, *bytes) = bytes.split_at(4);
-            let doc: u32 =
-                u32::from_le_bytes(doc_bytes.try_into().map_err(|_| ParseError::MissingBytes)?);
-            Ok(ColumnOperation::NewDoc(doc))
-        }
-    }
-}
-
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
-#[repr(u8)]
-pub enum SymbolType {
-    U64 = 1u8,
-    I64 = 2u8,
-    Float = 3u8,
-}
-
-impl TryFrom<u8> for SymbolType {
-    type Error = ParseError;
-
-    fn try_from(byte: u8) -> Result<Self, ParseError> {
-        match byte {
-            1u8 => Ok(SymbolType::U64),
-            2u8 => Ok(SymbolType::I64),
-            3u8 => Ok(SymbolType::Float),
-            _ => Err(ParseError::UnknownType(byte)),
-        }
-    }
-}
-
 fn encode_zig_zag(n: i64) -> u64 {
     ((n << 1) ^ (n >> 63)) as u64
 }
@@ -236,7 +210,7 @@ fn decode_zig_zag(n: u64) -> i64 {
 
 #[cfg(test)]
 mod tests {
-    use super::{SymbolType, *};
+    use super::*;
 
     #[track_caller]
     fn test_zig_zag_aux(val: i64) {
@@ -268,31 +242,27 @@ mod tests {
         }
     }
 
-    #[track_caller]
-    fn ser_deser_header_byte_aux(symbol_type: SymbolType, len: usize) {
-        let header_byte = compute_header_byte(symbol_type, len);
-        let (serdeser_numerical_type, serdeser_len) =
-            parse_header_byte(NonZeroU8::new(header_byte).unwrap()).unwrap();
-        assert_eq!(symbol_type, serdeser_numerical_type);
-        assert_eq!(len, serdeser_len);
-    }
-
     #[test]
     fn test_header_byte_serialization() {
-        for len in 1..9 {
-            ser_deser_header_byte_aux(SymbolType::Float, len);
-            ser_deser_header_byte_aux(SymbolType::I64, len);
-            ser_deser_header_byte_aux(SymbolType::U64, len);
+        for len in 0..=15 {
+            for typ_code in 0..=15 {
+                let header = ColumnOperationHeader { typ_code, len };
+                let header_code = header.to_code();
+                let serdeser_header = ColumnOperationHeader::from_code(header_code);
+                assert_eq!(header, serdeser_header);
+            }
         }
     }
 
     #[track_caller]
-    fn ser_deser_symbol(symbol: ColumnOperation<NumericalValue>) {
-        let buf = symbol.serialize();
-        let mut bytes = &buf.bytes[..];
+    fn ser_deser_symbol(column_op: ColumnOperation<NumericalValue>) {
+        let buf = column_op.serialize();
+        let mut buffer = buf.as_ref().to_vec();
+        buffer.extend_from_slice(b"234234");
+        let mut bytes = &buffer[..];
         let serdeser_symbol = ColumnOperation::deserialize(&mut bytes).unwrap();
-        assert_eq!(bytes.len() + buf.len, buf.bytes.len());
-        assert_eq!(symbol, serdeser_symbol);
+        assert_eq!(bytes.len() + buf.as_ref().len() as usize, buffer.len());
+        assert_eq!(column_op, serdeser_symbol);
     }
 
     #[test]
@@ -318,4 +288,24 @@ mod tests {
         ser_deser_symbol(ColumnOperation::Value(NumericalValue::U64(u64::MIN)));
         ser_deser_symbol(ColumnOperation::Value(NumericalValue::U64(u64::MAX)));
     }
+
+    fn test_column_operation_unordered_aux(val: u32, expected_len: usize) {
+        let column_op = ColumnOperation::Value(UnorderedId(val));
+        let minibuf = column_op.serialize();
+        assert_eq!(minibuf.as_ref().len() as usize, expected_len);
+        let mut buf = minibuf.as_ref().to_vec();
+        buf.extend_from_slice(&[2, 2, 2, 2, 2, 2]);
+        let mut cursor = &buf[..];
+        let column_op_serdeser: ColumnOperation<UnorderedId> =
+            ColumnOperation::deserialize(&mut cursor).unwrap();
+        assert_eq!(column_op_serdeser, ColumnOperation::Value(UnorderedId(val)));
+        assert_eq!(cursor.len() + expected_len, buf.len());
+    }
+
+    #[test]
+    fn test_column_operation_unordered() {
+        test_column_operation_unordered_aux(300u32, 3);
+        test_column_operation_unordered_aux(1u32, 2);
+        test_column_operation_unordered_aux(0u32, 1);
+    }
 }

columnar/src/writer/column_writers.rs

@@ -0,0 +1,270 @@
+use std::cmp::Ordering;
+
+use stacker::{ExpUnrolledLinkedList, MemoryArena};
+
+use crate::dictionary::{DictionaryBuilder, UnorderedId};
+use crate::writer::column_operation::{ColumnOperation, SymbolValue};
+use crate::{Cardinality, DocId, NumericalType, NumericalValue};
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[repr(u8)]
+enum DocumentStep {
+    SameDoc = 0,
+    NextDoc = 1,
+    SkippedDoc = 2,
+}
+
+#[inline(always)]
+fn delta_with_last_doc(last_doc_opt: Option<u32>, doc: u32) -> DocumentStep {
+    let expected_next_doc = last_doc_opt.map(|last_doc| last_doc + 1).unwrap_or(0u32);
+    match doc.cmp(&expected_next_doc) {
+        Ordering::Less => DocumentStep::SameDoc,
+        Ordering::Equal => DocumentStep::NextDoc,
+        Ordering::Greater => DocumentStep::SkippedDoc,
+    }
+}
+
+#[derive(Copy, Clone, Default)]
+pub struct ColumnWriter {
+    // Detected cardinality of the column so far.
+    cardinality: Cardinality,
+    // Last document inserted.
+    // None if no doc has been added yet.
+    last_doc_opt: Option<u32>,
+    // Buffer containing the serialized values.
+    values: ExpUnrolledLinkedList,
+}
+
+impl ColumnWriter {
+    /// Returns an iterator over the Symbol that have been recorded
+    /// for the given column.
+    pub(crate) fn operation_iterator<'a, V: SymbolValue>(
+        &self,
+        arena: &MemoryArena,
+        buffer: &'a mut Vec<u8>,
+    ) -> impl Iterator<Item = ColumnOperation<V>> + 'a {
+        buffer.clear();
+        self.values.read_to_end(arena, buffer);
+        let mut cursor: &[u8] = &buffer[..];
+        std::iter::from_fn(move || ColumnOperation::deserialize(&mut cursor))
+    }
+
+    /// Records a change of the document being recorded.
+    ///
+    /// This function will also update the cardinality of the column
+    /// if necessary.
+    pub(crate) fn record<S: SymbolValue>(&mut self, doc: DocId, value: S, arena: &mut MemoryArena) {
+        // Difference between `doc` and the last doc.
+        match delta_with_last_doc(self.last_doc_opt, doc) {
+            DocumentStep::SameDoc => {
+                // This is the last encounterred document.
+                self.cardinality = Cardinality::Multivalued;
+            }
+            DocumentStep::NextDoc => {
+                self.last_doc_opt = Some(doc);
+                self.write_symbol::<S>(ColumnOperation::NewDoc(doc), arena);
+            }
+            DocumentStep::SkippedDoc => {
+                self.cardinality = self.cardinality.max(Cardinality::Optional);
+                self.last_doc_opt = Some(doc);
+                self.write_symbol::<S>(ColumnOperation::NewDoc(doc), arena);
+            }
+        }
+        self.write_symbol(ColumnOperation::Value(value), arena);
+    }
+
+    // Get the cardinality.
+    // The overall number of docs in the column is necessary to
+    // deal with the case where the all docs contain 1 value, except some documents
+    // at the end of the column.
+    pub fn get_cardinality(&self, num_docs: DocId) -> Cardinality {
+        match delta_with_last_doc(self.last_doc_opt, num_docs) {
+            DocumentStep::SameDoc | DocumentStep::NextDoc => self.cardinality,
+            DocumentStep::SkippedDoc => self.cardinality.max(Cardinality::Optional),
+        }
+    }
+
+    /// Appends a new symbol to the `ColumnWriter`.
+    fn write_symbol<V: SymbolValue>(
+        &mut self,
+        column_operation: ColumnOperation<V>,
+        arena: &mut MemoryArena,
+    ) {
+        self.values
+            .writer(arena)
+            .extend_from_slice(column_operation.serialize().as_ref());
+    }
+}
+
+#[derive(Clone, Copy, Default)]
+pub(crate) struct NumericalColumnWriter {
+    compatible_numerical_types: CompatibleNumericalTypes,
+    column_writer: ColumnWriter,
+}
+
+/// State used to store what types are still acceptable
+/// after having seen a set of numerical values.
+#[derive(Clone, Copy)]
+pub(crate) struct CompatibleNumericalTypes {
+    all_values_within_i64_range: bool,
+    all_values_within_u64_range: bool,
+    // f64 is always acceptable.
+}
+
+impl Default for CompatibleNumericalTypes {
+    fn default() -> CompatibleNumericalTypes {
+        CompatibleNumericalTypes {
+            all_values_within_i64_range: true,
+            all_values_within_u64_range: true,
+        }
+    }
+}
+
+impl CompatibleNumericalTypes {
+    fn accept_value(&mut self, numerical_value: NumericalValue) {
+        match numerical_value {
+            NumericalValue::I64(val_i64) => {
+                let value_within_u64_range = val_i64 >= 0i64;
+                self.all_values_within_u64_range &= value_within_u64_range;
+            }
+            NumericalValue::U64(val_u64) => {
+                let value_within_i64_range = val_u64 < i64::MAX as u64;
+                self.all_values_within_i64_range &= value_within_i64_range;
+            }
+            NumericalValue::F64(_) => {
+                self.all_values_within_i64_range = false;
+                self.all_values_within_u64_range = false;
+            }
+        }
+    }
+
+    pub fn to_numerical_type(self) -> NumericalType {
+        if self.all_values_within_i64_range {
+            NumericalType::I64
+        } else if self.all_values_within_u64_range {
+            NumericalType::U64
+        } else {
+            NumericalType::F64
+        }
+    }
+}
+
+impl NumericalColumnWriter {
+    pub fn column_type_and_cardinality(&self, num_docs: DocId) -> (NumericalType, Cardinality) {
+        let numerical_type = self.compatible_numerical_types.to_numerical_type();
+        let cardinality = self.column_writer.get_cardinality(num_docs);
+        (numerical_type, cardinality)
+    }
+    pub fn record_numerical_value(
+        &mut self,
+        doc: DocId,
+        value: NumericalValue,
+        arena: &mut MemoryArena,
+    ) {
+        self.compatible_numerical_types.accept_value(value);
+        self.column_writer.record(doc, value, arena);
+    }
+
+    pub fn operation_iterator<'a>(
+        self,
+        arena: &MemoryArena,
+        buffer: &'a mut Vec<u8>,
+    ) -> impl Iterator<Item = ColumnOperation<NumericalValue>> + 'a {
+        self.column_writer.operation_iterator(arena, buffer)
+    }
+}
+
+#[derive(Copy, Clone, Default)]
+pub struct StrColumnWriter {
+    pub(crate) dictionary_id: u32,
+    pub(crate) column_writer: ColumnWriter,
+}
+
+impl StrColumnWriter {
+    pub fn with_dictionary_id(dictionary_id: u32) -> StrColumnWriter {
+        StrColumnWriter {
+            dictionary_id,
+            column_writer: Default::default(),
+        }
+    }
+
+    pub(crate) fn record_bytes(
+        &mut self,
+        doc: DocId,
+        bytes: &[u8],
+        dictionaries: &mut [DictionaryBuilder],
+        arena: &mut MemoryArena,
+    ) {
+        let unordered_id = dictionaries[self.dictionary_id as usize].get_or_allocate_id(bytes);
+        self.column_writer.record(doc, unordered_id, arena);
+    }
+
+    pub(crate) fn operation_iterator<'a>(
+        &self,
+        arena: &MemoryArena,
+        byte_buffer: &'a mut Vec<u8>,
+    ) -> impl Iterator<Item = ColumnOperation<UnorderedId>> + 'a {
+        self.column_writer.operation_iterator(arena, byte_buffer)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_delta_with_last_doc() {
+        assert_eq!(delta_with_last_doc(None, 0u32), DocumentStep::NextDoc);
+        assert_eq!(delta_with_last_doc(None, 1u32), DocumentStep::SkippedDoc);
+        assert_eq!(delta_with_last_doc(None, 2u32), DocumentStep::SkippedDoc);
+        assert_eq!(delta_with_last_doc(Some(0u32), 0u32), DocumentStep::SameDoc);
+        assert_eq!(delta_with_last_doc(Some(1u32), 1u32), DocumentStep::SameDoc);
+        assert_eq!(delta_with_last_doc(Some(1u32), 2u32), DocumentStep::NextDoc);
+        assert_eq!(
+            delta_with_last_doc(Some(1u32), 3u32),
+            DocumentStep::SkippedDoc
+        );
+        assert_eq!(
+            delta_with_last_doc(Some(1u32), 4u32),
+            DocumentStep::SkippedDoc
+        );
+    }
+
+    #[track_caller]
+    fn test_column_writer_coercion_iter_aux(
+        values: impl Iterator<Item = NumericalValue>,
+        expected_numerical_type: NumericalType,
+    ) {
+        let mut compatible_numerical_types = CompatibleNumericalTypes::default();
+        for value in values {
+            compatible_numerical_types.accept_value(value);
+        }
+        assert_eq!(
+            compatible_numerical_types.to_numerical_type(),
+            expected_numerical_type
+        );
+    }
+
+    #[track_caller]
+    fn test_column_writer_coercion_aux(
+        values: &[NumericalValue],
+        expected_numerical_type: NumericalType,
+    ) {
+        test_column_writer_coercion_iter_aux(values.iter().copied(), expected_numerical_type);
+        test_column_writer_coercion_iter_aux(values.iter().rev().copied(), expected_numerical_type);
+    }
+
+    #[test]
+    fn test_column_writer_coercion() {
+        test_column_writer_coercion_aux(&[], NumericalType::I64);
+        test_column_writer_coercion_aux(&[1i64.into()], NumericalType::I64);
+        test_column_writer_coercion_aux(&[1u64.into()], NumericalType::I64);
+        // We don't detect exact integer at the moment. We could!
+        test_column_writer_coercion_aux(&[1f64.into()], NumericalType::F64);
+        test_column_writer_coercion_aux(&[u64::MAX.into()], NumericalType::U64);
+        test_column_writer_coercion_aux(&[(i64::MAX as u64).into()], NumericalType::U64);
+        test_column_writer_coercion_aux(&[(1u64 << 63).into()], NumericalType::U64);
+        test_column_writer_coercion_aux(&[1i64.into(), 1u64.into()], NumericalType::I64);
+        test_column_writer_coercion_aux(&[u64::MAX.into(), (-1i64).into()], NumericalType::F64);
+    }
+}

columnar/src/writer/mod.rs

@@ -1,196 +1,42 @@
 mod column_operation;
+mod column_writers;
+mod serializer;
 mod value_index;
 
 use std::io::{self, Write};
 
 use column_operation::ColumnOperation;
-use common::CountingWriter;
 use fastfield_codecs::serialize::ValueIndexInfo;
 use fastfield_codecs::{Column, MonotonicallyMappableToU64, VecColumn};
-use ordered_float::NotNan;
-use stacker::{Addr, ArenaHashMap, ExpUnrolledLinkedList, MemoryArena};
+use serializer::ColumnarSerializer;
+use stacker::{Addr, ArenaHashMap, MemoryArena};
 
-use crate::column_type_header::{ColumnType, ColumnTypeAndCardinality};
+use crate::column_type_header::{ColumnType, ColumnTypeAndCardinality, GeneralType};
 use crate::dictionary::{DictionaryBuilder, IdMapping, UnorderedId};
 use crate::value::{Coerce, NumericalType, NumericalValue};
-use crate::writer::column_operation::SymbolValue;
+use crate::writer::column_writers::{ColumnWriter, NumericalColumnWriter, StrColumnWriter};
 use crate::writer::value_index::{IndexBuilder, SpareIndexBuilders};
-use crate::{Cardinality, ColumnarSerializer, DocId};
+use crate::{Cardinality, DocId};
 
-#[derive(Copy, Clone, Default)]
-struct ColumnWriter {
-    // Detected cardinality of the column so far.
-    cardinality: Cardinality,
-    // Last document inserted.
-    // None if no doc has been added yet.
-    last_doc_opt: Option<u32>,
-    // Buffer containing the serialized values.
-    values: ExpUnrolledLinkedList,
-}
+/// Threshold above which a column data will be compressed
+/// using ZSTD.
+const COLUMN_COMPRESSION_THRESHOLD: usize = 100_000;
 
-#[derive(Clone, Copy, Default)]
-pub struct NumericalColumnWriter {
-    compatible_numerical_types: CompatibleNumericalTypes,
-    column_writer: ColumnWriter,
-}
-
-#[derive(Clone, Copy)]
-struct CompatibleNumericalTypes {
-    all_values_within_i64_range: bool,
-    all_values_within_u64_range: bool,
-}
-
-impl Default for CompatibleNumericalTypes {
-    fn default() -> CompatibleNumericalTypes {
-        CompatibleNumericalTypes {
-            all_values_within_i64_range: true,
-            all_values_within_u64_range: true,
-        }
-    }
-}
-
-impl CompatibleNumericalTypes {
-    pub fn accept_value(&mut self, numerical_value: NumericalValue) {
-        match numerical_value {
-            NumericalValue::I64(val_i64) => {
-                let value_within_u64_range = val_i64 >= 0i64;
-                self.all_values_within_u64_range &= value_within_u64_range;
-            }
-            NumericalValue::U64(val_u64) => {
-                let value_within_i64_range = val_u64 < i64::MAX as u64;
-                self.all_values_within_i64_range &= value_within_i64_range;
-            }
-            NumericalValue::F64(_) => {
-                self.all_values_within_i64_range = false;
-                self.all_values_within_u64_range = false;
-            }
-        }
-    }
-
-    pub fn to_numerical_type(self) -> NumericalType {
-        if self.all_values_within_i64_range {
-            NumericalType::I64
-        } else if self.all_values_within_u64_range {
-            NumericalType::U64
-        } else {
-            NumericalType::F64
-        }
-    }
-}
-
-impl NumericalColumnWriter {
-    pub fn record_numerical_value(
-        &mut self,
-        doc: DocId,
-        value: NumericalValue,
-        arena: &mut MemoryArena,
-    ) {
-        self.compatible_numerical_types.accept_value(value);
-        self.column_writer.record(doc, value, arena);
-    }
-}
-
-impl ColumnWriter {
-    fn symbol_iterator<'a, V: SymbolValue>(
-        &self,
-        arena: &MemoryArena,
-        buffer: &'a mut Vec<u8>,
-    ) -> impl Iterator<Item = ColumnOperation<V>> + 'a {
-        buffer.clear();
-        self.values.read_to_end(arena, buffer);
-        let mut cursor: &[u8] = &buffer[..];
-        std::iter::from_fn(move || {
-            if cursor.is_empty() {
-                return None;
-            }
-            let symbol = ColumnOperation::deserialize(&mut cursor)
-                .expect("Failed to deserialize symbol from in-memory. This should never happen.");
-            Some(symbol)
-        })
-    }
-
-    fn delta_with_last_doc(&self, doc: DocId) -> u32 {
-        self.last_doc_opt
-            .map(|last_doc| doc - last_doc)
-            .unwrap_or(doc + 1u32)
-    }
-
-    /// Records a change of the document being recorded.
-    ///
-    /// This function will also update the cardinality of the column
-    /// if necessary.
-    fn record(&mut self, doc: DocId, value: NumericalValue, arena: &mut MemoryArena) {
-        // Difference between `doc` and the last doc.
-        match self.delta_with_last_doc(doc) {
-            0 => {
-                // This is the last encounterred document.
-                self.cardinality = Cardinality::Multivalued;
-            }
-            1 => {
-                self.last_doc_opt = Some(doc);
-                self.write_symbol::<NumericalValue>(ColumnOperation::NewDoc(doc), arena);
-            }
-            _ => {
-                self.cardinality = self.cardinality.max(Cardinality::Optional);
-                self.last_doc_opt = Some(doc);
-                self.write_symbol::<NumericalValue>(ColumnOperation::NewDoc(doc), arena);
-            }
-        }
-        self.write_symbol(ColumnOperation::Value(value), arena);
-    }
-
-    // Get the cardinality.
-    // The overall number of docs in the column is necessary to
-    // deal with the case where the all docs contain 1 value, except some documents
-    // at the end of the column.
-    fn get_cardinality(&self, num_docs: DocId) -> Cardinality {
-        if self.delta_with_last_doc(num_docs) > 1 {
-            self.cardinality.max(Cardinality::Optional)
-        } else {
-            self.cardinality
-        }
-    }
-
-    fn write_symbol<V: SymbolValue>(
-        &mut self,
-        symbol: ColumnOperation<V>,
-        arena: &mut MemoryArena,
-    ) {
-        self.values
-            .writer(arena)
-            .extend_from_slice(symbol.serialize().as_slice());
-    }
-}
-
-#[derive(Copy, Clone, Default)]
-pub struct BytesColumnWriter {
-    dictionary_id: u32,
-    column_writer: ColumnWriter,
-}
-
-impl BytesColumnWriter {
-    pub fn with_dictionary_id(dictionary_id: u32) -> BytesColumnWriter {
-        BytesColumnWriter {
-            dictionary_id,
-            column_writer: Default::default(),
-        }
-    }
-
-    pub fn record_bytes(
-        &mut self,
-        doc: DocId,
-        bytes: &[u8],
-        dictionaries: &mut [DictionaryBuilder],
-        arena: &mut MemoryArena,
-    ) {
-        let unordered_id = dictionaries[self.dictionary_id as usize].get_or_allocate_id(bytes);
-        let numerical_value = NumericalValue::U64(unordered_id.0 as u64);
-        self.column_writer.record(doc, numerical_value, arena);
-    }
+/// This is a set of buffers that are only here
+/// to limit the amount of allocation.
+#[derive(Default)]
+struct SpareBuffers {
+    value_index_builders: SpareIndexBuilders,
+    i64_values: Vec<i64>,
+    u64_values: Vec<u64>,
+    f64_values: Vec<f64>,
+    bool_values: Vec<bool>,
+    column_buffer: Vec<u8>,
 }
 
 pub struct ColumnarWriter {
     numerical_field_hash_map: ArenaHashMap,
+    bool_field_hash_map: ArenaHashMap,
     bytes_field_hash_map: ArenaHashMap,
     arena: MemoryArena,
     // Dictionaries used to store dictionary-encoded values.
@@ -198,19 +44,11 @@ pub struct ColumnarWriter {
     buffers: SpareBuffers,
 }
 
-#[derive(Default)]
-struct SpareBuffers {
-    byte_buffer: Vec<u8>,
-    value_index_builders: SpareIndexBuilders,
-    i64_values: Vec<i64>,
-    u64_values: Vec<u64>,
-    f64_values: Vec<ordered_float::NotNan<f64>>,
-}
-
 impl Default for ColumnarWriter {
     fn default() -> Self {
         ColumnarWriter {
             numerical_field_hash_map: ArenaHashMap::new(10_000),
+            bool_field_hash_map: ArenaHashMap::new(10_000),
             bytes_field_hash_map: ArenaHashMap::new(10_000),
             dictionaries: Vec::new(),
             arena: MemoryArena::default(),
@@ -219,235 +57,304 @@ impl Default for ColumnarWriter {
     }
 }
 
-#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug)]
-enum BytesOrNumerical {
-    Bytes,
-    Numerical,
-}
-
 impl ColumnarWriter {
-    pub fn record_numerical(&mut self, doc: DocId, key: &[u8], numerical_value: NumericalValue) {
+    pub fn record_numerical(
+        &mut self,
+        doc: DocId,
+        column_name: &str,
+        numerical_value: NumericalValue,
+    ) {
+        assert!(
+            !column_name.as_bytes().contains(&0u8),
+            "key may not contain the 0 byte"
+        );
         let (hash_map, arena) = (&mut self.numerical_field_hash_map, &mut self.arena);
-        hash_map.mutate_or_create(key, |column_opt: Option<NumericalColumnWriter>| {
-            let mut column: NumericalColumnWriter = column_opt.unwrap_or_default();
-            column.record_numerical_value(doc, numerical_value, arena);
-            column
-        });
+        hash_map.mutate_or_create(
+            column_name.as_bytes(),
+            |column_opt: Option<NumericalColumnWriter>| {
+                let mut column: NumericalColumnWriter = column_opt.unwrap_or_default();
+                column.record_numerical_value(doc, numerical_value, arena);
+                column
+            },
+        );
     }
 
-    pub fn record_bytes(&mut self, doc: DocId, key: &[u8], value: &[u8]) {
+    pub fn record_bool(&mut self, doc: DocId, column_name: &str, val: bool) {
+        assert!(
+            !column_name.as_bytes().contains(&0u8),
+            "key may not contain the 0 byte"
+        );
+        let (hash_map, arena) = (&mut self.bool_field_hash_map, &mut self.arena);
+        hash_map.mutate_or_create(
+            column_name.as_bytes(),
+            |column_opt: Option<ColumnWriter>| {
+                let mut column: ColumnWriter = column_opt.unwrap_or_default();
+                column.record(doc, val, arena);
+                column
+            },
+        );
+    }
+
+    pub fn record_str(&mut self, doc: DocId, column_name: &str, value: &[u8]) {
+        assert!(
+            !column_name.as_bytes().contains(&0u8),
+            "key may not contain the 0 byte"
+        );
         let (hash_map, arena, dictionaries) = (
             &mut self.bytes_field_hash_map,
             &mut self.arena,
             &mut self.dictionaries,
         );
-        hash_map.mutate_or_create(key, |column_opt: Option<BytesColumnWriter>| {
-            let mut column: BytesColumnWriter = column_opt.unwrap_or_else(|| {
-                let dictionary_id = dictionaries.len() as u32;
-                dictionaries.push(DictionaryBuilder::default());
-                BytesColumnWriter::with_dictionary_id(dictionary_id)
-            });
-            column.record_bytes(doc, value, dictionaries, arena);
-            column
-        });
+        hash_map.mutate_or_create(
+            column_name.as_bytes(),
+            |column_opt: Option<StrColumnWriter>| {
+                let mut column: StrColumnWriter = column_opt.unwrap_or_else(|| {
+                    let dictionary_id = dictionaries.len() as u32;
+                    dictionaries.push(DictionaryBuilder::default());
+                    StrColumnWriter::with_dictionary_id(dictionary_id)
+                });
+                column.record_bytes(doc, value, dictionaries, arena);
+                column
+            },
+        );
     }
 
-    pub fn serialize<W: io::Write>(
-        &mut self,
-        num_docs: DocId,
-        mut serializer: ColumnarSerializer<W>,
-    ) -> io::Result<()> {
-        let mut field_columns: Vec<(&[u8], BytesOrNumerical, Addr)> = self
+    pub fn serialize(&mut self, num_docs: DocId, wrt: &mut dyn io::Write) -> io::Result<()> {
+        let mut serializer = ColumnarSerializer::new(wrt);
+        let mut field_columns: Vec<(&[u8], GeneralType, Addr)> = self
             .numerical_field_hash_map
             .iter()
-            .map(|(term, addr, _)| (term, BytesOrNumerical::Numerical, addr))
+            .map(|(term, addr, _)| (term, GeneralType::Numerical, addr))
             .collect();
         field_columns.extend(
             self.bytes_field_hash_map
                 .iter()
-                .map(|(term, addr, _)| (term, BytesOrNumerical::Bytes, addr)),
+                .map(|(term, addr, _)| (term, GeneralType::Str, addr)),
         );
-        let mut key_buffer = Vec::new();
-        field_columns.sort_unstable_by_key(|(key, col_type, _)| (*key, *col_type));
+        field_columns.extend(
+            self.bool_field_hash_map
+                .iter()
+                .map(|(term, addr, _)| (term, GeneralType::Bool, addr)),
+        );
+        field_columns.sort_unstable_by_key(|(column_name, col_type, _)| (*column_name, *col_type));
         let (arena, buffers, dictionaries) = (&self.arena, &mut self.buffers, &self.dictionaries);
-        for (key, bytes_or_numerical, addr) in field_columns {
-            let wrt = serializer.wrt();
-            let start_offset = wrt.written_bytes();
-            let column_type_and_cardinality: ColumnTypeAndCardinality =
-                match bytes_or_numerical {
-                BytesOrNumerical::Bytes => {
-                    let BytesColumnWriter { dictionary_id, column_writer } =
-                        self.bytes_field_hash_map.read(addr);
+        let mut symbol_byte_buffer: Vec<u8> = Vec::new();
+        for (column_name, bytes_or_numerical, addr) in field_columns {
+            match bytes_or_numerical {
+                GeneralType::Bool => {
+                    let column_writer: ColumnWriter = self.bool_field_hash_map.read(addr);
+                    let cardinality = column_writer.get_cardinality(num_docs);
+                    let column_type_and_cardinality = ColumnTypeAndCardinality {
+                        cardinality,
+                        typ: ColumnType::Bool,
+                    };
+                    let column_serializer =
+                        serializer.serialize_column(column_name, column_type_and_cardinality);
+                    serialize_bool_column(
+                        cardinality,
+                        num_docs,
+                        column_writer.operation_iterator(arena, &mut symbol_byte_buffer),
+                        buffers,
+                        column_serializer,
+                    )?;
+                }
+                GeneralType::Str => {
+                    let str_column_writer: StrColumnWriter = self.bytes_field_hash_map.read(addr);
                     let dictionary_builder =
-                        &dictionaries[dictionary_id as usize];
+                        &dictionaries[str_column_writer.dictionary_id as usize];
+                    let cardinality = str_column_writer.column_writer.get_cardinality(num_docs);
+                    let column_type_and_cardinality = ColumnTypeAndCardinality {
+                        cardinality,
+                        typ: ColumnType::Bytes,
+                    };
+                    let column_serializer =
+                        serializer.serialize_column(column_name, column_type_and_cardinality);
                     serialize_bytes_column(
-                        &column_writer,
+                        cardinality,
                         num_docs,
                         dictionary_builder,
-                        arena,
+                        str_column_writer.operation_iterator(arena, &mut symbol_byte_buffer),
                         buffers,
-                        wrt,
+                        column_serializer,
                     )?;
-                    ColumnTypeAndCardinality {
-                        cardinality: column_writer.get_cardinality(num_docs),
-                        typ: ColumnType::Bytes,
-                    }
                 }
-                BytesOrNumerical::Numerical => {
-                    let NumericalColumnWriter { compatible_numerical_types, column_writer  } =
+                GeneralType::Numerical => {
+                    let numerical_column_writer: NumericalColumnWriter =
                         self.numerical_field_hash_map.read(addr);
-                    let cardinality = column_writer.get_cardinality(num_docs);
-                    let numerical_type = compatible_numerical_types.to_numerical_type();
-                    serialize_numerical_column(
-                        cardinality,
-                        numerical_type,
-                        &column_writer,
-                        num_docs,
-                        arena,
-                        buffers,
-                        wrt,
-                    )?;
-                    ColumnTypeAndCardinality {
+                    let (numerical_type, cardinality) =
+                        numerical_column_writer.column_type_and_cardinality(num_docs);
+                    let column_type_and_cardinality = ColumnTypeAndCardinality {
                         cardinality,
                         typ: ColumnType::Numerical(numerical_type),
-                    }
+                    };
+                    let column_serializer =
+                        serializer.serialize_column(column_name, column_type_and_cardinality);
+                    serialize_numerical_column(
+                        cardinality,
+                        num_docs,
+                        numerical_type,
+                        numerical_column_writer.operation_iterator(arena, &mut symbol_byte_buffer),
+                        buffers,
+                        column_serializer,
+                    )?;
                 }
             };
-            let end_offset = wrt.written_bytes();
-            let key_with_type = prepare_key(key, column_type_and_cardinality, &mut key_buffer);
-            serializer.record_column_offsets(key_with_type, start_offset..end_offset)?;
         }
         serializer.finalize()?;
         Ok(())
     }
 }
 
-/// Returns a key consisting of the concatenation of the key and the column_type_and_cardinality
-/// code.
-fn prepare_key<'a>(
-    key: &[u8],
-    column_type_cardinality: ColumnTypeAndCardinality,
-    buffer: &'a mut Vec<u8>,
-) -> &'a [u8] {
-    buffer.clear();
-    buffer.extend_from_slice(key);
-    buffer.push(0u8);
-    buffer.push(column_type_cardinality.to_code());
-    &buffer[..]
+fn compress_and_write_column<W: io::Write>(column_bytes: &[u8], wrt: &mut W) -> io::Result<()> {
+    if column_bytes.len() >= COLUMN_COMPRESSION_THRESHOLD {
+        wrt.write_all(&[1])?;
+        let mut encoder = zstd::Encoder::new(wrt, 3)?;
+        encoder.write_all(column_bytes)?;
+        encoder.finish()?;
+    } else {
+        wrt.write_all(&[0])?;
+        wrt.write_all(column_bytes)?;
+    }
+    Ok(())
 }
 
 fn serialize_bytes_column<W: io::Write>(
-    column_writer: &ColumnWriter,
+    cardinality: Cardinality,
     num_docs: DocId,
     dictionary_builder: &DictionaryBuilder,
-    arena: &MemoryArena,
+    operation_it: impl Iterator<Item = ColumnOperation<UnorderedId>>,
     buffers: &mut SpareBuffers,
-    wrt: &mut CountingWriter<W>,
+    mut wrt: W,
 ) -> io::Result<()> {
-    let start_offset = wrt.written_bytes();
-    let id_mapping: IdMapping = dictionary_builder.serialize(wrt)?;
-    let dictionary_num_bytes: u32 = (wrt.written_bytes() - start_offset) as u32;
-    let cardinality = column_writer.get_cardinality(num_docs);
     let SpareBuffers {
-        byte_buffer,
         value_index_builders,
         u64_values,
+        column_buffer,
         ..
     } = buffers;
-    let symbol_iterator = column_writer
-        .symbol_iterator(arena, byte_buffer)
-        .map(|symbol: ColumnOperation<UnorderedId>| {
-            // We map unordered ids to ordered ids.
-            match symbol {
-                ColumnOperation::Value(unordered_id) => {
-                    let ordered_id = id_mapping.to_ord(unordered_id);
-                    ColumnOperation::Value(ordered_id.0 as u64)
-                }
-                ColumnOperation::NewDoc(doc) => ColumnOperation::NewDoc(doc),
+    column_buffer.clear();
+    let id_mapping: IdMapping = dictionary_builder.serialize(column_buffer)?;
+    let dictionary_num_bytes: u32 = column_buffer.len() as u32;
+    let operation_iterator = operation_it.map(|symbol: ColumnOperation<UnorderedId>| {
+        // We map unordered ids to ordered ids.
+        match symbol {
+            ColumnOperation::Value(unordered_id) => {
+                let ordered_id = id_mapping.to_ord(unordered_id);
+                ColumnOperation::Value(ordered_id.0 as u64)
             }
-        });
+            ColumnOperation::NewDoc(doc) => ColumnOperation::NewDoc(doc),
+        }
+    });
     serialize_column(
-        symbol_iterator,
+        operation_iterator,
         cardinality,
         num_docs,
         value_index_builders,
         u64_values,
-        wrt,
+        column_buffer,
     )?;
-    wrt.write_all(&dictionary_num_bytes.to_le_bytes()[..])?;
+    column_buffer.write_all(&dictionary_num_bytes.to_le_bytes()[..])?;
+    compress_and_write_column(column_buffer, &mut wrt)?;
     Ok(())
 }
 
 fn serialize_numerical_column<W: io::Write>(
     cardinality: Cardinality,
-    numerical_type: NumericalType,
-    column_writer: &ColumnWriter,
     num_docs: DocId,
-    arena: &MemoryArena,
+    numerical_type: NumericalType,
+    op_iterator: impl Iterator<Item = ColumnOperation<NumericalValue>>,
     buffers: &mut SpareBuffers,
-    wrt: &mut W,
+    mut wrt: W,
 ) -> io::Result<()> {
     let SpareBuffers {
-        byte_buffer,
         value_index_builders,
         u64_values,
         i64_values,
         f64_values,
+        column_buffer,
+        ..
     } = buffers;
-    let symbol_iterator = column_writer.symbol_iterator(arena, byte_buffer);
+    column_buffer.clear();
     match numerical_type {
         NumericalType::I64 => {
             serialize_column(
-                coerce_numerical_symbol::<i64>(symbol_iterator),
+                coerce_numerical_symbol::<i64>(op_iterator),
                 cardinality,
                 num_docs,
                 value_index_builders,
                 i64_values,
-                wrt,
+                column_buffer,
             )?;
         }
         NumericalType::U64 => {
             serialize_column(
-                coerce_numerical_symbol::<u64>(symbol_iterator),
+                coerce_numerical_symbol::<u64>(op_iterator),
                 cardinality,
                 num_docs,
                 value_index_builders,
                 u64_values,
-                wrt,
+                column_buffer,
             )?;
         }
         NumericalType::F64 => {
             serialize_column(
-                coerce_numerical_symbol::<NotNan<f64>>(symbol_iterator),
+                coerce_numerical_symbol::<f64>(op_iterator),
                 cardinality,
                 num_docs,
                 value_index_builders,
                 f64_values,
-                wrt,
+                column_buffer,
             )?;
         }
     };
+    compress_and_write_column(column_buffer, &mut wrt)?;
+    Ok(())
+}
+
+fn serialize_bool_column<W: io::Write>(
+    cardinality: Cardinality,
+    num_docs: DocId,
+    column_operations_it: impl Iterator<Item = ColumnOperation<bool>>,
+    buffers: &mut SpareBuffers,
+    mut wrt: W,
+) -> io::Result<()> {
+    let SpareBuffers {
+        value_index_builders,
+        bool_values,
+        column_buffer,
+        ..
+    } = buffers;
+    column_buffer.clear();
+    serialize_column(
+        column_operations_it,
+        cardinality,
+        num_docs,
+        value_index_builders,
+        bool_values,
+        column_buffer,
+    )?;
+    compress_and_write_column(column_buffer, &mut wrt)?;
     Ok(())
 }
 
 fn serialize_column<
-    T: Copy + Ord + Default + Send + Sync + MonotonicallyMappableToU64,
-    W: io::Write,
+    T: Copy + Default + std::fmt::Debug + Send + Sync + MonotonicallyMappableToU64 + PartialOrd,
 >(
-    symbol_iterator: impl Iterator<Item = ColumnOperation<T>>,
+    op_iterator: impl Iterator<Item = ColumnOperation<T>>,
     cardinality: Cardinality,
     num_docs: DocId,
     value_index_builders: &mut SpareIndexBuilders,
     values: &mut Vec<T>,
-    wrt: &mut W,
+    wrt: &mut Vec<u8>,
 ) -> io::Result<()>
 where
     for<'a> VecColumn<'a, T>: Column<T>,
 {
+    values.clear();
     match cardinality {
         Cardinality::Required => {
-            consume_symbol_iterator(
-                symbol_iterator,
+            consume_operation_iterator(
+                op_iterator,
                 value_index_builders.borrow_required_index_builder(),
                 values,
             );
@@ -459,7 +366,7 @@ where
         }
         Cardinality::Optional => {
             let optional_index_builder = value_index_builders.borrow_optional_index_builder();
-            consume_symbol_iterator(symbol_iterator, optional_index_builder, values);
+            consume_operation_iterator(op_iterator, optional_index_builder, values);
             let optional_index = optional_index_builder.finish(num_docs);
             fastfield_codecs::serialize::serialize_new(
                 ValueIndexInfo::SingleValue(Box::new(optional_index)),
@@ -470,7 +377,7 @@ where
         }
         Cardinality::Multivalued => {
             let multivalued_index_builder = value_index_builders.borrow_multivalued_index_builder();
-            consume_symbol_iterator(symbol_iterator, multivalued_index_builder, values);
+            consume_operation_iterator(op_iterator, multivalued_index_builder, values);
             let multivalued_index = multivalued_index_builder.finish(num_docs);
             fastfield_codecs::serialize::serialize_new(
                 ValueIndexInfo::MultiValue(Box::new(multivalued_index)),
@@ -484,10 +391,10 @@ where
 }
 
 fn coerce_numerical_symbol<T>(
-    symbol_iterator: impl Iterator<Item = ColumnOperation<NumericalValue>>,
+    operation_iterator: impl Iterator<Item = ColumnOperation<NumericalValue>>,
 ) -> impl Iterator<Item = ColumnOperation<T>>
 where T: Coerce {
-    symbol_iterator.map(|symbol| match symbol {
+    operation_iterator.map(|symbol| match symbol {
         ColumnOperation::NewDoc(doc) => ColumnOperation::NewDoc(doc),
         ColumnOperation::Value(numerical_value) => {
             ColumnOperation::Value(Coerce::coerce(numerical_value))
@@ -495,12 +402,12 @@ where T: Coerce {
     })
 }
 
-fn consume_symbol_iterator<T, TIndexBuilder: IndexBuilder>(
-    symbol_iterator: impl Iterator<Item = ColumnOperation<T>>,
+fn consume_operation_iterator<T: std::fmt::Debug, TIndexBuilder: IndexBuilder>(
+    operation_iterator: impl Iterator<Item = ColumnOperation<T>>,
     index_builder: &mut TIndexBuilder,
     values: &mut Vec<T>,
 ) {
-    for symbol in symbol_iterator {
+    for symbol in operation_iterator {
         match symbol {
             ColumnOperation::NewDoc(doc) => {
                 index_builder.record_doc(doc);
@@ -515,42 +422,24 @@ fn consume_symbol_iterator<T, TIndexBuilder: IndexBuilder>(
 
 #[cfg(test)]
 mod tests {
-
-    use ordered_float::NotNan;
+    use column_operation::ColumnOperation;
     use stacker::MemoryArena;
 
-    use super::prepare_key;
-    use crate::column_type_header::{ColumnType, ColumnTypeAndCardinality};
-    use crate::value::{NumericalType, NumericalValue};
-    use crate::writer::column_operation::ColumnOperation;
-    use crate::writer::CompatibleNumericalTypes;
+    use super::*;
+    use crate::value::NumericalValue;
     use crate::Cardinality;
 
-    #[test]
-    fn test_prepare_key_bytes() {
-        let mut buffer: Vec<u8> = b"somegarbage".to_vec();
-        let column_type_and_cardinality = ColumnTypeAndCardinality {
-            typ: ColumnType::Bytes,
-            cardinality: Cardinality::Optional,
-        };
-        let prepared_key = prepare_key(b"root\0child", column_type_and_cardinality, &mut buffer);
-        assert_eq!(prepared_key.len(), 12);
-        assert_eq!(&prepared_key[..10], b"root\0child");
-        assert_eq!(prepared_key[10], 0u8);
-        assert_eq!(prepared_key[11], column_type_and_cardinality.to_code());
-    }
-
     #[test]
     fn test_column_writer_required_simple() {
         let mut arena = MemoryArena::default();
         let mut column_writer = super::ColumnWriter::default();
-        column_writer.record(0u32, 14i64.into(), &mut arena);
-        column_writer.record(1u32, 15i64.into(), &mut arena);
-        column_writer.record(2u32, (-16i64).into(), &mut arena);
+        column_writer.record(0u32, NumericalValue::from(14i64), &mut arena);
+        column_writer.record(1u32, NumericalValue::from(15i64), &mut arena);
+        column_writer.record(2u32, NumericalValue::from(-16i64), &mut arena);
         assert_eq!(column_writer.get_cardinality(3), Cardinality::Required);
         let mut buffer = Vec::new();
         let symbols: Vec<ColumnOperation<NumericalValue>> = column_writer
-            .symbol_iterator(&mut arena, &mut buffer)
+            .operation_iterator(&mut arena, &mut buffer)
             .collect();
         assert_eq!(symbols.len(), 6);
         assert!(matches!(symbols[0], ColumnOperation::NewDoc(0u32)));
@@ -574,12 +463,12 @@ mod tests {
     fn test_column_writer_optional_cardinality_missing_first() {
         let mut arena = MemoryArena::default();
         let mut column_writer = super::ColumnWriter::default();
-        column_writer.record(1u32, 15i64.into(), &mut arena);
-        column_writer.record(2u32, (-16i64).into(), &mut arena);
+        column_writer.record(1u32, NumericalValue::from(15i64), &mut arena);
+        column_writer.record(2u32, NumericalValue::from(-16i64), &mut arena);
         assert_eq!(column_writer.get_cardinality(3), Cardinality::Optional);
         let mut buffer = Vec::new();
         let symbols: Vec<ColumnOperation<NumericalValue>> = column_writer
-            .symbol_iterator(&mut arena, &mut buffer)
+            .operation_iterator(&mut arena, &mut buffer)
             .collect();
         assert_eq!(symbols.len(), 4);
         assert!(matches!(symbols[0], ColumnOperation::NewDoc(1u32)));
@@ -598,11 +487,11 @@ mod tests {
     fn test_column_writer_optional_cardinality_missing_last() {
         let mut arena = MemoryArena::default();
         let mut column_writer = super::ColumnWriter::default();
-        column_writer.record(0u32, 15i64.into(), &mut arena);
+        column_writer.record(0u32, NumericalValue::from(15i64), &mut arena);
         assert_eq!(column_writer.get_cardinality(2), Cardinality::Optional);
         let mut buffer = Vec::new();
         let symbols: Vec<ColumnOperation<NumericalValue>> = column_writer
-            .symbol_iterator(&mut arena, &mut buffer)
+            .operation_iterator(&mut arena, &mut buffer)
             .collect();
         assert_eq!(symbols.len(), 2);
         assert!(matches!(symbols[0], ColumnOperation::NewDoc(0u32)));
@@ -616,12 +505,12 @@ mod tests {
     fn test_column_writer_multivalued() {
         let mut arena = MemoryArena::default();
         let mut column_writer = super::ColumnWriter::default();
-        column_writer.record(0u32, 16i64.into(), &mut arena);
-        column_writer.record(0u32, 17i64.into(), &mut arena);
+        column_writer.record(0u32, NumericalValue::from(16i64), &mut arena);
+        column_writer.record(0u32, NumericalValue::from(17i64), &mut arena);
         assert_eq!(column_writer.get_cardinality(1), Cardinality::Multivalued);
         let mut buffer = Vec::new();
         let symbols: Vec<ColumnOperation<NumericalValue>> = column_writer
-            .symbol_iterator(&mut arena, &mut buffer)
+            .operation_iterator(&mut arena, &mut buffer)
             .collect();
         assert_eq!(symbols.len(), 3);
         assert!(matches!(symbols[0], ColumnOperation::NewDoc(0u32)));
@@ -634,42 +523,4 @@ mod tests {
             ColumnOperation::Value(NumericalValue::I64(17i64))
         ));
     }
-
-    #[track_caller]
-    fn test_column_writer_coercion_iter_aux(
-        values: impl Iterator<Item = NumericalValue>,
-        expected_numerical_type: NumericalType,
-    ) {
-        let mut compatible_numerical_types = CompatibleNumericalTypes::default();
-        for value in values {
-            compatible_numerical_types.accept_value(value);
-        }
-        assert_eq!(
-            compatible_numerical_types.to_numerical_type(),
-            expected_numerical_type
-        );
-    }
-
-    #[track_caller]
-    fn test_column_writer_coercion_aux(
-        values: &[NumericalValue],
-        expected_numerical_type: NumericalType,
-    ) {
-        test_column_writer_coercion_iter_aux(values.iter().copied(), expected_numerical_type);
-        test_column_writer_coercion_iter_aux(values.iter().rev().copied(), expected_numerical_type);
-    }
-
-    #[test]
-    fn test_column_writer_coercion() {
-        test_column_writer_coercion_aux(&[], NumericalType::I64);
-        test_column_writer_coercion_aux(&[1i64.into()], NumericalType::I64);
-        test_column_writer_coercion_aux(&[1u64.into()], NumericalType::I64);
-        // We don't detect exact integer at the moment. We could!
-        test_column_writer_coercion_aux(&[NotNan::new(1f64).unwrap().into()], NumericalType::F64);
-        test_column_writer_coercion_aux(&[u64::MAX.into()], NumericalType::U64);
-        test_column_writer_coercion_aux(&[(i64::MAX as u64).into()], NumericalType::U64);
-        test_column_writer_coercion_aux(&[(1u64 << 63).into()], NumericalType::U64);
-        test_column_writer_coercion_aux(&[1i64.into(), 1u64.into()], NumericalType::I64);
-        test_column_writer_coercion_aux(&[u64::MAX.into(), (-1i64).into()], NumericalType::F64);
-    }
 }

columnar/src/writer/serializer.rs

@@ -0,0 +1,116 @@
+use std::io;
+use std::io::Write;
+
+use common::CountingWriter;
+use sstable::value::RangeValueWriter;
+use sstable::RangeSSTable;
+
+use crate::column_type_header::ColumnTypeAndCardinality;
+
+pub struct ColumnarSerializer<W: io::Write> {
+    wrt: CountingWriter<W>,
+    sstable_range: sstable::Writer<Vec<u8>, RangeValueWriter>,
+    prepare_key_buffer: Vec<u8>,
+}
+
+/// Returns a key consisting of the concatenation of the key and the column_type_and_cardinality
+/// code.
+fn prepare_key<'a>(
+    key: &[u8],
+    column_type_cardinality: ColumnTypeAndCardinality,
+    buffer: &'a mut Vec<u8>,
+) {
+    buffer.clear();
+    buffer.extend_from_slice(key);
+    buffer.push(0u8);
+    buffer.push(column_type_cardinality.to_code());
+}
+
+impl<W: io::Write> ColumnarSerializer<W> {
+    pub(crate) fn new(wrt: W) -> ColumnarSerializer<W> {
+        let sstable_range: sstable::Writer<Vec<u8>, RangeValueWriter> =
+            sstable::Dictionary::<RangeSSTable>::builder(Vec::with_capacity(100_000)).unwrap();
+        ColumnarSerializer {
+            wrt: CountingWriter::wrap(wrt),
+            sstable_range,
+            prepare_key_buffer: Vec::new(),
+        }
+    }
+
+    pub fn serialize_column<'a>(
+        &'a mut self,
+        column_name: &[u8],
+        column_type_cardinality: ColumnTypeAndCardinality,
+    ) -> impl io::Write + 'a {
+        let start_offset = self.wrt.written_bytes();
+        prepare_key(
+            column_name,
+            column_type_cardinality,
+            &mut self.prepare_key_buffer,
+        );
+        ColumnSerializer {
+            columnar_serializer: self,
+            start_offset,
+        }
+    }
+
+    pub(crate) fn finalize(mut self) -> io::Result<()> {
+        let sstable_bytes: Vec<u8> = self.sstable_range.finish()?;
+        let sstable_num_bytes: u64 = sstable_bytes.len() as u64;
+        self.wrt.write_all(&sstable_bytes)?;
+        self.wrt.write_all(&sstable_num_bytes.to_le_bytes()[..])?;
+        Ok(())
+    }
+}
+
+struct ColumnSerializer<'a, W: io::Write> {
+    columnar_serializer: &'a mut ColumnarSerializer<W>,
+    start_offset: u64,
+}
+
+impl<'a, W: io::Write> Drop for ColumnSerializer<'a, W> {
+    fn drop(&mut self) {
+        let end_offset: u64 = self.columnar_serializer.wrt.written_bytes();
+        let byte_range = self.start_offset..end_offset;
+        self.columnar_serializer.sstable_range.insert_cannot_fail(
+            &self.columnar_serializer.prepare_key_buffer[..],
+            &byte_range,
+        );
+        self.columnar_serializer.prepare_key_buffer.clear();
+    }
+}
+
+impl<'a, W: io::Write> io::Write for ColumnSerializer<'a, W> {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.columnar_serializer.wrt.write(buf)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.columnar_serializer.wrt.flush()
+    }
+
+    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
+        self.columnar_serializer.wrt.write_all(buf)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::column_type_header::ColumnType;
+    use crate::Cardinality;
+
+    #[test]
+    fn test_prepare_key_bytes() {
+        let mut buffer: Vec<u8> = b"somegarbage".to_vec();
+        let column_type_and_cardinality = ColumnTypeAndCardinality {
+            typ: ColumnType::Bytes,
+            cardinality: Cardinality::Optional,
+        };
+        prepare_key(b"root\0child", column_type_and_cardinality, &mut buffer);
+        assert_eq!(buffer.len(), 12);
+        assert_eq!(&buffer[..10], b"root\0child");
+        assert_eq!(buffer[10], 0u8);
+        assert_eq!(buffer[11], column_type_and_cardinality.to_code());
+    }
+}

common/src/file_slice.rs

@@ -24,8 +24,11 @@ pub trait FileHandle: 'static + Send + Sync + HasLen + fmt::Debug {
     fn read_bytes(&self, range: Range<usize>) -> io::Result<OwnedBytes>;
 
     #[doc(hidden)]
-    async fn read_bytes_async(&self, byte_range: Range<usize>) -> io::Result<OwnedBytes> {
-        self.read_bytes(byte_range)
+    async fn read_bytes_async(&self, _byte_range: Range<usize>) -> io::Result<OwnedBytes> {
+        Err(io::Error::new(
+            io::ErrorKind::Unsupported,
+            "Async read is not supported.",
+        ))
     }
 }
 
@@ -36,7 +39,6 @@ impl FileHandle for &'static [u8] {
         Ok(OwnedBytes::new(bytes))
     }
 
-    #[cfg(feature = "quickwit")]
     async fn read_bytes_async(&self, byte_range: Range<usize>) -> io::Result<OwnedBytes> {
         Ok(self.read_bytes(byte_range)?)
     }
@@ -65,7 +67,16 @@ impl fmt::Debug for FileSlice {
     }
 }
 
-#[inline]
+/// Takes a range, a `RangeBounds` object, and returns
+/// a `Range` that corresponds to the relative application of the
+/// `RangeBounds` object to the original `Range`.
+///
+/// For instance, combine_ranges(`[2..11)`, `[5..7]`) returns `[7..10]`
+/// as it reads, what is the sub-range that starts at the 5 element of
+/// `[2..11)` and ends at the 9th element included.
+///
+/// This function panics, if the result would suggest something outside
+/// of the bounds of the original range.
 fn combine_ranges<R: RangeBounds<usize>>(orig_range: Range<usize>, rel_range: R) -> Range<usize> {
     let start: usize = orig_range.start
         + match rel_range.start_bound().cloned() {
@@ -213,7 +224,6 @@ impl FileHandle for FileSlice {
         self.read_bytes_slice(range)
     }
 
-    #[cfg(feature = "quickwit")]
     async fn read_bytes_async(&self, byte_range: Range<usize>) -> io::Result<OwnedBytes> {
         self.read_bytes_slice_async(byte_range).await
     }
@@ -231,16 +241,15 @@ impl FileHandle for OwnedBytes {
         Ok(self.slice(range))
     }
 
-    #[cfg(feature = "quickwit")]
     async fn read_bytes_async(&self, range: Range<usize>) -> io::Result<OwnedBytes> {
-        let bytes = self.read_bytes(range)?;
-        Ok(bytes)
+        self.read_bytes(range)
     }
 }
 
 #[cfg(test)]
 mod tests {
     use std::io;
+    use std::ops::Bound;
     use std::sync::Arc;
 
     use super::{FileHandle, FileSlice};
@@ -323,6 +332,11 @@ mod tests {
         assert_eq!(combine_ranges(1..3, 1..), 2..3);
         assert_eq!(combine_ranges(1..4, ..2), 1..3);
         assert_eq!(combine_ranges(3..10, 2..5), 5..8);
+        assert_eq!(combine_ranges(2..11, 5..=7), 7..10);
+        assert_eq!(
+            combine_ranges(2..11, (Bound::Excluded(5), Bound::Unbounded)),
+            8..11
+        );
     }
 
     #[test]

common/src/lib.rs

@@ -10,7 +10,7 @@ mod serialize;
 mod vint;
 mod writer;
 pub use bitset::*;
-pub use ownedbytes::OwnedBytes;
+pub use ownedbytes::{OwnedBytes, StableDeref};
 pub use serialize::{BinarySerializable, DeserializeFrom, FixedSize};
 pub use vint::{
     deserialize_vint_u128, read_u32_vint, read_u32_vint_no_advance, serialize_vint_u128,

fastfield_codecs/Cargo.toml

@@ -14,14 +14,12 @@ repository = "https://github.com/quickwit-oss/tantivy"
 [dependencies]
 common = { version = "0.5", path = "../common/", package = "tantivy-common" }
 tantivy-bitpacker = { version= "0.3", path = "../bitpacker/" }
-ownedbytes = { version = "0.5", path = "../ownedbytes" }
 prettytable-rs = {version="0.9.0", optional= true}
 rand = {version="0.8.3", optional= true}
 fastdivide = "0.4"
 log = "0.4"
 itertools = { version = "0.10.3" }
 measure_time = { version="0.8.2", optional=true}
-ordered-float = "3.4"
 
 [dev-dependencies]
 more-asserts = "0.3.0"

fastfield_codecs/benches/bench.rs

@@ -7,8 +7,8 @@ mod tests {
     use std::iter;
     use std::sync::Arc;
 
+    use common::OwnedBytes;
     use fastfield_codecs::*;
-    use ownedbytes::OwnedBytes;
     use rand::prelude::*;
     use test::Bencher;
 

fastfield_codecs/src/bitpacked.rs

@@ -1,6 +1,6 @@
 use std::io::{self, Write};
 
-use ownedbytes::OwnedBytes;
+use common::OwnedBytes;
 use tantivy_bitpacker::{compute_num_bits, BitPacker, BitUnpacker};
 
 use crate::serialize::NormalizedHeader;

fastfield_codecs/src/blockwise_linear.rs

@@ -1,8 +1,7 @@
 use std::sync::Arc;
 use std::{io, iter};
 
-use common::{BinarySerializable, CountingWriter, DeserializeFrom};
-use ownedbytes::OwnedBytes;
+use common::{BinarySerializable, CountingWriter, DeserializeFrom, OwnedBytes};
 use tantivy_bitpacker::{compute_num_bits, BitPacker, BitUnpacker};
 
 use crate::line::Line;
@@ -47,7 +46,7 @@ impl FastFieldCodec for BlockwiseLinearCodec {
     type Reader = BlockwiseLinearReader;
 
     fn open_from_bytes(
-        bytes: ownedbytes::OwnedBytes,
+        bytes: common::OwnedBytes,
         normalized_header: NormalizedHeader,
     ) -> io::Result<Self::Reader> {
         let footer_len: u32 = (&bytes[bytes.len() - 4..]).deserialize()?;
@@ -171,15 +170,18 @@ impl Column for BlockwiseLinearReader {
         interpoled_val.wrapping_add(bitpacked_diff)
     }
 
+    #[inline(always)]
     fn min_value(&self) -> u64 {
         // The BlockwiseLinearReader assumes a normalized vector.
         0u64
     }
 
+    #[inline(always)]
     fn max_value(&self) -> u64 {
         self.normalized_header.max_value
     }
 
+    #[inline(always)]
     fn num_vals(&self) -> u32 {
         self.normalized_header.num_vals
     }

fastfield_codecs/src/column.rs

@@ -135,7 +135,7 @@ impl<'a, T: Copy + PartialOrd + Send + Sync> Column<T> for VecColumn<'a, T> {
     }
 }
 
-impl<'a, T: Copy + Ord + Default, V> From<&'a V> for VecColumn<'a, T>
+impl<'a, T: Copy + PartialOrd + Default, V> From<&'a V> for VecColumn<'a, T>
 where V: AsRef<[T]> + ?Sized
 {
     fn from(values: &'a V) -> Self {

fastfield_codecs/src/compact_space/mod.rs

@@ -17,8 +17,7 @@ use std::{
     ops::{Range, RangeInclusive},
 };
 
-use common::{BinarySerializable, CountingWriter, VInt, VIntU128};
-use ownedbytes::OwnedBytes;
+use common::{BinarySerializable, CountingWriter, OwnedBytes, VInt, VIntU128};
 use tantivy_bitpacker::{self, BitPacker, BitUnpacker};
 
 use crate::compact_space::build_compact_space::get_compact_space;

fastfield_codecs/src/format_version.rs

@@ -1,7 +1,6 @@
 use std::io;
 
-use common::BinarySerializable;
-use ownedbytes::OwnedBytes;
+use common::{BinarySerializable, OwnedBytes};
 
 const MAGIC_NUMBER: u16 = 4335u16;
 const FASTFIELD_FORMAT_VERSION: u8 = 1;

fastfield_codecs/src/gcd.rs

@@ -45,7 +45,7 @@ mod tests {
     use std::io;
     use std::num::NonZeroU64;
 
-    use ownedbytes::OwnedBytes;
+    use common::OwnedBytes;
 
     use crate::gcd::{compute_gcd, find_gcd};
     use crate::{FastFieldCodecType, VecColumn};

fastfield_codecs/src/lib.rs

@@ -18,7 +18,7 @@ use std::io;
 use std::io::Write;
 use std::sync::Arc;
 
-use common::BinarySerializable;
+use common::{BinarySerializable, OwnedBytes};
 use compact_space::CompactSpaceDecompressor;
 use format_version::read_format_version;
 use monotonic_mapping::{
@@ -26,7 +26,6 @@ use monotonic_mapping::{
     StrictlyMonotonicMappingToInternalBaseval, StrictlyMonotonicMappingToInternalGCDBaseval,
 };
 use null_index_footer::read_null_index_footer;
-use ownedbytes::OwnedBytes;
 use serialize::{Header, U128Header};
 
 mod bitpacked;
@@ -45,8 +44,6 @@ mod column;
 mod gcd;
 pub mod serialize;
 
-pub use ordered_float;
-
 use self::bitpacked::BitpackedCodec;
 use self::blockwise_linear::BlockwiseLinearCodec;
 pub use self::column::{monotonic_map_column, Column, IterColumn, VecColumn};
@@ -438,7 +435,7 @@ mod tests {
 mod bench {
     use std::sync::Arc;
 
-    use ownedbytes::OwnedBytes;
+    use common::OwnedBytes;
     use rand::rngs::StdRng;
     use rand::{Rng, SeedableRng};
     use test::{self, Bencher};

fastfield_codecs/src/linear.rs

@@ -1,7 +1,6 @@
 use std::io::{self, Write};
 
-use common::BinarySerializable;
-use ownedbytes::OwnedBytes;
+use common::{BinarySerializable, OwnedBytes};
 use tantivy_bitpacker::{compute_num_bits, BitPacker, BitUnpacker};
 
 use crate::line::Line;
@@ -25,13 +24,13 @@ impl Column for LinearReader {
         interpoled_val.wrapping_add(bitpacked_diff)
     }
 
-    #[inline]
+    #[inline(always)]
     fn min_value(&self) -> u64 {
         // The LinearReader assumes a normalized vector.
         0u64
     }
 
-    #[inline]
+    #[inline(always)]
     fn max_value(&self) -> u64 {
         self.header.max_value
     }

fastfield_codecs/src/main.rs

@@ -6,10 +6,10 @@ use std::io::BufRead;
 use std::net::{IpAddr, Ipv6Addr};
 use std::str::FromStr;
 
+use common::OwnedBytes;
 use fastfield_codecs::{open_u128, serialize_u128, Column, FastFieldCodecType, VecColumn};
 use itertools::Itertools;
 use measure_time::print_time;
-use ownedbytes::OwnedBytes;
 use prettytable::{Cell, Row, Table};
 
 fn print_set_stats(ip_addrs: &[u128]) {

fastfield_codecs/src/monotonic_mapping.rs

@@ -1,7 +1,6 @@
 use std::marker::PhantomData;
 
 use fastdivide::DividerU64;
-use ordered_float::NotNan;
 
 use crate::MonotonicallyMappableToU128;
 
@@ -57,10 +56,12 @@ impl<T> From<T> for StrictlyMonotonicMappingInverter<T> {
 impl<From, To, T> StrictlyMonotonicFn<To, From> for StrictlyMonotonicMappingInverter<T>
 where T: StrictlyMonotonicFn<From, To>
 {
+    #[inline(always)]
     fn mapping(&self, val: To) -> From {
         self.orig_mapping.inverse(val)
     }
 
+    #[inline(always)]
     fn inverse(&self, val: From) -> To {
         self.orig_mapping.mapping(val)
     }
@@ -83,10 +84,12 @@ impl<External: MonotonicallyMappableToU128, T: MonotonicallyMappableToU128>
     StrictlyMonotonicFn<External, u128> for StrictlyMonotonicMappingToInternal<T>
 where T: MonotonicallyMappableToU128
 {
+    #[inline(always)]
     fn mapping(&self, inp: External) -> u128 {
         External::to_u128(inp)
     }
 
+    #[inline(always)]
     fn inverse(&self, out: u128) -> External {
         External::from_u128(out)
     }
@@ -96,10 +99,12 @@ impl<External: MonotonicallyMappableToU64, T: MonotonicallyMappableToU64>
     StrictlyMonotonicFn<External, u64> for StrictlyMonotonicMappingToInternal<T>
 where T: MonotonicallyMappableToU64
 {
+    #[inline(always)]
     fn mapping(&self, inp: External) -> u64 {
         External::to_u64(inp)
     }
 
+    #[inline(always)]
     fn inverse(&self, out: u64) -> External {
         External::from_u64(out)
     }
@@ -127,11 +132,13 @@ impl StrictlyMonotonicMappingToInternalGCDBaseval {
 impl<External: MonotonicallyMappableToU64> StrictlyMonotonicFn<External, u64>
     for StrictlyMonotonicMappingToInternalGCDBaseval
 {
+    #[inline(always)]
     fn mapping(&self, inp: External) -> u64 {
         self.gcd_divider
             .divide(External::to_u64(inp) - self.min_value)
     }
 
+    #[inline(always)]
     fn inverse(&self, out: u64) -> External {
         External::from_u64(self.min_value + out * self.gcd)
     }
@@ -142,6 +149,7 @@ pub(crate) struct StrictlyMonotonicMappingToInternalBaseval {
     min_value: u64,
 }
 impl StrictlyMonotonicMappingToInternalBaseval {
+    #[inline(always)]
     pub(crate) fn new(min_value: u64) -> Self {
         Self { min_value }
     }
@@ -150,20 +158,24 @@ impl StrictlyMonotonicMappingToInternalBaseval {
 impl<External: MonotonicallyMappableToU64> StrictlyMonotonicFn<External, u64>
     for StrictlyMonotonicMappingToInternalBaseval
 {
+    #[inline(always)]
     fn mapping(&self, val: External) -> u64 {
         External::to_u64(val) - self.min_value
     }
 
+    #[inline(always)]
     fn inverse(&self, val: u64) -> External {
         External::from_u64(self.min_value + val)
     }
 }
 
 impl MonotonicallyMappableToU64 for u64 {
+    #[inline(always)]
     fn to_u64(self) -> u64 {
         self
     }
 
+    #[inline(always)]
     fn from_u64(val: u64) -> Self {
         val
     }
@@ -196,51 +208,22 @@ impl MonotonicallyMappableToU64 for bool {
 // TODO remove me.
 // Tantivy should refuse NaN values and work with NotNaN internally.
 impl MonotonicallyMappableToU64 for f64 {
+    #[inline(always)]
     fn to_u64(self) -> u64 {
         common::f64_to_u64(self)
     }
 
+    #[inline(always)]
     fn from_u64(val: u64) -> Self {
         common::u64_to_f64(val)
     }
 }
 
-impl MonotonicallyMappableToU64 for ordered_float::NotNan<f64> {
-    fn to_u64(self) -> u64 {
-        common::f64_to_u64(self.into_inner())
-    }
-
-    fn from_u64(val: u64) -> Self {
-        NotNan::new(common::u64_to_f64(val)).expect("Invalid NotNaN f64 value.")
-    }
-}
-
 #[cfg(test)]
 mod tests {
 
     use super::*;
 
-    #[test]
-    fn test_from_u64_pos_inf() {
-        let inf_as_u64 = common::f64_to_u64(f64::INFINITY);
-        let inf_back_to_f64 = NotNan::from_u64(inf_as_u64);
-        assert_eq!(inf_back_to_f64, NotNan::new(f64::INFINITY).unwrap());
-    }
-
-    #[test]
-    fn test_from_u64_neg_inf() {
-        let inf_as_u64 = common::f64_to_u64(-f64::INFINITY);
-        let inf_back_to_f64 = NotNan::from_u64(inf_as_u64);
-        assert_eq!(inf_back_to_f64, NotNan::new(-f64::INFINITY).unwrap());
-    }
-
-    #[test]
-    #[should_panic(expected = "Invalid NotNaN")]
-    fn test_from_u64_nan_panics() {
-        let nan_as_u64 = common::f64_to_u64(f64::NAN);
-        NotNan::from_u64(nan_as_u64);
-    }
-
     #[test]
     fn strictly_monotonic_test() {
         // identity mapping

fastfield_codecs/src/null_index/dense.rs

@@ -1,9 +1,8 @@
 use std::convert::TryInto;
 use std::io::{self, Write};
 
-use common::BinarySerializable;
+use common::{BinarySerializable, OwnedBytes};
 use itertools::Itertools;
-use ownedbytes::OwnedBytes;
 
 use super::{get_bit_at, set_bit_at};
 

fastfield_codecs/src/null_index/sparse.rs

@@ -1,7 +1,6 @@
 use std::io::{self, Write};
 
-use common::BitSet;
-use ownedbytes::OwnedBytes;
+use common::{BitSet, OwnedBytes};
 
 use super::{serialize_dense_codec, DenseCodec};
 
@@ -59,6 +58,7 @@ enum SparseCodecBlockVariant {
 
 impl SparseCodecBlockVariant {
     /// The number of non-null values that preceeded that block.
+    #[inline]
     fn offset(&self) -> u32 {
         match self {
             SparseCodecBlockVariant::Empty { offset } => *offset,

fastfield_codecs/src/null_index_footer.rs

@@ -1,8 +1,7 @@
 use std::io::{self, Write};
 use std::ops::Range;
 
-use common::{BinarySerializable, CountingWriter, VInt};
-use ownedbytes::OwnedBytes;
+use common::{BinarySerializable, CountingWriter, OwnedBytes, VInt};
 
 #[derive(Debug, Clone, Copy, Eq, PartialEq)]
 pub(crate) enum FastFieldCardinality {

fastfield_codecs/src/serialize.rs

@@ -1,10 +1,28 @@
+// Copyright (C) 2022 Quickwit, Inc.
+//
+// Quickwit is offered under the AGPL v3.0 and as commercial software.
+// For commercial licensing, contact us at hello@quickwit.io.
+//
+// AGPL:
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+
 use std::io;
 use std::num::NonZeroU64;
 use std::sync::Arc;
 
-use common::{BinarySerializable, VInt};
+use common::{BinarySerializable, OwnedBytes, VInt};
 use log::warn;
-use ownedbytes::OwnedBytes;
 
 use crate::bitpacked::BitpackedCodec;
 use crate::blockwise_linear::BlockwiseLinearCodec;
@@ -184,6 +202,7 @@ pub enum ValueIndexInfo<'a> {
     SingleValue(Box<dyn SingleValueIndexInfo + 'a>),
 }
 
+// TODO Remove me
 impl Default for ValueIndexInfo<'static> {
     fn default() -> Self {
         struct Dummy {}

src/directory/mmap_directory.rs

@@ -6,10 +6,10 @@ use std::path::{Path, PathBuf};
 use std::sync::{Arc, RwLock, Weak};
 use std::{fmt, result};
 
+use common::StableDeref;
 use fs2::FileExt;
 use memmap2::Mmap;
 use serde::{Deserialize, Serialize};
-use stable_deref_trait::StableDeref;
 use tempfile::TempDir;
 
 use crate::core::META_FILEPATH;

src/directory/mod.rs

@@ -20,8 +20,7 @@ use std::io::BufWriter;
 use std::path::PathBuf;
 
 pub use common::file_slice::{FileHandle, FileSlice};
-pub use common::{AntiCallToken, TerminatingWrite};
-pub use ownedbytes::OwnedBytes;
+pub use common::{AntiCallToken, OwnedBytes, TerminatingWrite};
 
 pub(crate) use self::composite_file::{CompositeFile, CompositeWrite};
 pub use self::directory::{Directory, DirectoryClone, DirectoryLock};

src/fastfield/alive_bitset.rs

@@ -1,8 +1,7 @@
 use std::io;
 use std::io::Write;
 
-use common::{intersect_bitsets, BitSet, ReadOnlyBitSet};
-use ownedbytes::OwnedBytes;
+use common::{intersect_bitsets, BitSet, OwnedBytes, ReadOnlyBitSet};
 
 use crate::space_usage::ByteCount;
 use crate::DocId;

src/fastfield/multivalued/index.rs

@@ -80,6 +80,7 @@ impl MultiValueIndex {
     ///
     /// TODO: Instead of a linear scan we can employ a exponential search into binary search to
     /// match a docid to its value position.
+    #[allow(clippy::bool_to_int_with_if)]
     pub(crate) fn positions_to_docids(&self, doc_id_range: Range<u32>, positions: &mut Vec<u32>) {
         if positions.is_empty() {
             return;

src/indexer/stamper.rs

@@ -20,7 +20,7 @@ mod atomic_impl {
         }
 
         pub fn fetch_add(&self, val: u64, order: Ordering) -> u64 {
-            self.0.fetch_add(val, order) as u64
+            self.0.fetch_add(val, order)
         }
 
         pub fn revert(&self, val: u64, order: Ordering) -> u64 {

src/postings/serializer.rs

@@ -213,21 +213,21 @@ impl<'a> FieldSerializer<'a> {
         fail_point!("FieldSerializer::close_term", |msg: Option<String>| {
             Err(io::Error::new(io::ErrorKind::Other, format!("{:?}", msg)))
         });
-        if !self.term_open {
-            return Ok(());
+        if self.term_open {
+            self.postings_serializer
+                .close_term(self.current_term_info.doc_freq)?;
+            self.current_term_info.postings_range.end =
+                self.postings_serializer.written_bytes() as usize;
+
+            if let Some(positions_serializer) = self.positions_serializer_opt.as_mut() {
+                positions_serializer.close_term()?;
+                self.current_term_info.positions_range.end =
+                    positions_serializer.written_bytes() as usize;
+            }
+            self.term_dictionary_builder
+                .insert_value(&self.current_term_info)?;
+            self.term_open = false;
         }
-        self.postings_serializer
-            .close_term(self.current_term_info.doc_freq)?;
-        self.current_term_info.postings_range.end =
-            self.postings_serializer.written_bytes() as usize;
-        if let Some(positions_serializer) = self.positions_serializer_opt.as_mut() {
-            positions_serializer.close_term()?;
-            self.current_term_info.positions_range.end =
-                positions_serializer.written_bytes() as usize;
-        }
-        self.term_dictionary_builder
-            .insert_value(&self.current_term_info)?;
-        self.term_open = false;
         Ok(())
     }
 

src/query/disjunction_max_query.rs

@@ -3,7 +3,7 @@ use tantivy_query_grammar::Occur;
 use crate::query::{BooleanWeight, DisjunctionMaxCombiner, EnableScoring, Query, Weight};
 use crate::{Score, Term};
 
-/// The disjunction max query кeturns documents matching one or more wrapped queries,
+/// The disjunction max query returns documents matching one or more wrapped queries,
 /// called query clauses or clauses.
 ///
 /// If a returned document matches multiple query clauses,

src/query/range_query_ip_fastfield.rs

@@ -280,9 +280,7 @@ impl DocSet for IpRangeDocSet {
 
     #[inline]
     fn doc(&self) -> DocId {
-        self.loaded_docs
-            .current()
-            .unwrap_or(TERMINATED)
+        self.loaded_docs.current().unwrap_or(TERMINATED)
     }
 
     /// Advances the `DocSet` forward until reaching the target, or going to the

src/store/reader.rs

@@ -4,9 +4,8 @@ use std::ops::{AddAssign, Range};
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::{Arc, Mutex};
 
-use common::{BinarySerializable, HasLen};
+use common::{BinarySerializable, HasLen, OwnedBytes};
 use lru::LruCache;
-use ownedbytes::OwnedBytes;
 
 use super::footer::DocStoreFooter;
 use super::index::SkipIndex;

src/termdict/sstable_termdict/mod.rs

@@ -1,7 +1,6 @@
 use std::io;
 
 mod merger;
-mod termdict;
 
 use std::iter::ExactSizeIterator;
 
@@ -13,26 +12,39 @@ use tantivy_fst::automaton::AlwaysMatch;
 pub use self::merger::TermMerger;
 use crate::postings::TermInfo;
 
+/// The term dictionary contains all of the terms in
+/// `tantivy index` in a sorted manner.
+///
+/// The `Fst` crate is used to associate terms to their
+/// respective `TermOrdinal`. The `TermInfoStore` then makes it
+/// possible to fetch the associated `TermInfo`.
 pub type TermDictionary = sstable::Dictionary<TermSSTable>;
-pub type TermDictionaryBuilder<W> = sstable::Writer<W, TermInfoWriter>;
+
+/// Builder for the new term dictionary.
+pub type TermDictionaryBuilder<W> = sstable::Writer<W, TermInfoValueWriter>;
+
+/// `TermStreamer` acts as a cursor over a range of terms of a segment.
+/// Terms are guaranteed to be sorted.
 pub type TermStreamer<'a, A = AlwaysMatch> = sstable::Streamer<'a, TermSSTable, A>;
 
+/// SSTable used to store TermInfo objects.
 pub struct TermSSTable;
 
 impl SSTable for TermSSTable {
     type Value = TermInfo;
-    type ValueReader = TermInfoReader;
-    type ValueWriter = TermInfoWriter;
+    type ValueReader = TermInfoValueReader;
+    type ValueWriter = TermInfoValueWriter;
 }
 
 #[derive(Default)]
-pub struct TermInfoReader {
+pub struct TermInfoValueReader {
     term_infos: Vec<TermInfo>,
 }
 
-impl ValueReader for TermInfoReader {
+impl ValueReader for TermInfoValueReader {
     type Value = TermInfo;
 
+    #[inline(always)]
     fn value(&self, idx: usize) -> &TermInfo {
         &self.term_infos[idx]
     }
@@ -64,18 +76,18 @@ impl ValueReader for TermInfoReader {
 }
 
 #[derive(Default)]
-pub struct TermInfoWriter {
+pub struct TermInfoValueWriter {
     term_infos: Vec<TermInfo>,
 }
 
-impl ValueWriter for TermInfoWriter {
+impl ValueWriter for TermInfoValueWriter {
     type Value = TermInfo;
 
     fn write(&mut self, term_info: &TermInfo) {
         self.term_infos.push(term_info.clone());
     }
 
-    fn serialize_block(&mut self, buffer: &mut Vec<u8>) {
+    fn serialize_block(&self, buffer: &mut Vec<u8>) {
         VInt(self.term_infos.len() as u64).serialize_into_vec(buffer);
         if self.term_infos.is_empty() {
             return;
@@ -87,6 +99,9 @@ impl ValueWriter for TermInfoWriter {
             VInt(term_info.postings_range.len() as u64).serialize_into_vec(buffer);
             VInt(term_info.positions_range.len() as u64).serialize_into_vec(buffer);
         }
+    }
+
+    fn clear(&mut self) {
         self.term_infos.clear();
     }
 }
@@ -96,11 +111,11 @@ mod tests {
     use sstable::value::{ValueReader, ValueWriter};
 
     use crate::postings::TermInfo;
-    use crate::termdict::sstable_termdict::TermInfoReader;
+    use crate::termdict::sstable_termdict::TermInfoValueReader;
 
     #[test]
     fn test_block_terminfos() {
-        let mut term_info_writer = super::TermInfoWriter::default();
+        let mut term_info_writer = super::TermInfoValueWriter::default();
         term_info_writer.write(&TermInfo {
             doc_freq: 120u32,
             postings_range: 17..45,
@@ -118,8 +133,7 @@ mod tests {
         });
         let mut buffer = Vec::new();
         term_info_writer.serialize_block(&mut buffer);
-        // let mut block_reader = make_block_reader(&buffer[..]);
-        let mut term_info_reader = TermInfoReader::default();
+        let mut term_info_reader = TermInfoValueReader::default();
         let num_bytes: usize = term_info_reader.load(&buffer[..]).unwrap();
         assert_eq!(
             term_info_reader.value(0),

src/termdict/sstable_termdict/termdict.rs

@@ -1,11 +0,0 @@
-use sstable::SSTable;
-
-use crate::postings::TermInfo;
-use crate::termdict::sstable_termdict::{TermInfoReader, TermInfoWriter};
-
-pub struct TermInfoSSTable;
-impl SSTable for TermInfoSSTable {
-    type Value = TermInfo;
-    type ValueReader = TermInfoReader;
-    type ValueWriter = TermInfoWriter;
-}

sstable/Cargo.toml

@@ -2,6 +2,7 @@
 name = "tantivy-sstable"
 version = "0.1.0"
 edition = "2021"
+license = "MIT"
 
 [dependencies]
 common = {path="../common", package="tantivy-common"}
@@ -11,3 +12,10 @@ tantivy-fst = "0.4"
 
 [dev-dependencies]
 proptest = "1"
+criterion = "0.4"
+names = "0.14"
+rand = "0.8"
+
+[[bench]]
+name = "stream_bench"
+harness = false

sstable/README.md

@@ -0,0 +1,28 @@
+# SSTable
+
+The `tantivy-sstable` crate is yet another sstable crate.
+
+It has been designed to be used in `quickwit`:
+- as an alternative to the default tantivy fst dictionary.
+- as a way to store the column index for dynamic fast fields.
+
+The benefit compared to the fst crate is locality.
+Searching a key in the fst crate requires downloading the entire dictionary.
+
+Once the sstable index is downloaded, running a `get` in the sstable
+crate only requires a single fetch.
+
+Right now, the block index and the default block size have been thought
+for quickwit, and the performance of a get is very bad.
+
+# Sorted strings?
+
+SSTable stands for Sorted String Table.
+Strings have to be insert in sorted order.
+
+That sorted order is used in different ways:
+- it makes gets and streaming ranges of keys
+possible.
+- it allows incremental encoding of the keys
+- the front compression is leveraged to optimize
+the intersection with an automaton

sstable/benches/stream_bench.rs

@@ -0,0 +1,87 @@
+use std::collections::BTreeSet;
+use std::io;
+
+use common::file_slice::FileSlice;
+use criterion::{criterion_group, criterion_main, Criterion};
+use rand::rngs::StdRng;
+use rand::{Rng, SeedableRng};
+use tantivy_sstable::{self, Dictionary, MonotonicU64SSTable};
+
+const CHARSET: &'static [u8] = b"abcdefghij";
+
+fn generate_key(rng: &mut impl Rng) -> String {
+    let len = rng.gen_range(3..12);
+    std::iter::from_fn(|| {
+        let idx = rng.gen_range(0..CHARSET.len());
+        Some(CHARSET[idx] as char)
+    })
+    .take(len)
+    .collect()
+}
+
+fn prepare_sstable() -> io::Result<Dictionary<MonotonicU64SSTable>> {
+    let mut rng = StdRng::from_seed([3u8; 32]);
+    let mut els = BTreeSet::new();
+    while els.len() < 100_000 {
+        els.insert(generate_key(&mut rng));
+    }
+    let mut dictionary_builder = Dictionary::<MonotonicU64SSTable>::builder(Vec::new())?;
+    for (ord, word) in els.iter().enumerate() {
+        dictionary_builder.insert(word, &(ord as u64))?;
+    }
+    let buffer = dictionary_builder.finish()?;
+    let dictionary = Dictionary::open(FileSlice::from(buffer))?;
+    Ok(dictionary)
+}
+
+fn stream_bench(
+    dictionary: &Dictionary<MonotonicU64SSTable>,
+    lower: &[u8],
+    upper: &[u8],
+    do_scan: bool,
+) -> usize {
+    let mut stream = dictionary
+        .range()
+        .ge(lower)
+        .lt(upper)
+        .into_stream()
+        .unwrap();
+    if !do_scan {
+        return 0;
+    }
+    let mut count = 0;
+    while stream.advance() {
+        count += 1;
+    }
+    count
+}
+
+pub fn criterion_benchmark(c: &mut Criterion) {
+    let dict = prepare_sstable().unwrap();
+    c.bench_function("short_scan_init", |b| {
+        b.iter(|| stream_bench(&dict, b"fa", b"fana", false))
+    });
+    c.bench_function("short_scan_init_and_scan", |b| {
+        b.iter(|| {
+            assert_eq!(stream_bench(&dict, b"fa", b"faz", true), 971);
+        })
+    });
+    c.bench_function("full_scan_init_and_scan_full_with_bound", |b| {
+        b.iter(|| {
+            assert_eq!(stream_bench(&dict, b"", b"z", true), 100_000);
+        })
+    });
+    c.bench_function("full_scan_init_and_scan_full_no_bounds", |b| {
+        b.iter(|| {
+            let mut stream = dict.stream().unwrap();
+            let mut count = 0;
+            while stream.advance() {
+                count += 1;
+            }
+            count
+        })
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);

sstable/src/block_reader.rs

@@ -1,4 +1,5 @@
 use std::io;
+use std::ops::Range;
 
 pub struct BlockReader<'a> {
     buffer: Vec<u8>,
@@ -29,8 +30,8 @@ impl<'a> BlockReader<'a> {
     }
 
     #[inline(always)]
-    pub fn buffer_from_to(&self, start: usize, end: usize) -> &[u8] {
-        &self.buffer[start..end]
+    pub fn buffer_from_to(&self, range: Range<usize>) -> &[u8] {
+        &self.buffer[range]
     }
 
     pub fn read_block(&mut self) -> io::Result<bool> {
@@ -51,14 +52,17 @@ impl<'a> BlockReader<'a> {
         Ok(true)
     }
 
+    #[inline(always)]
     pub fn offset(&self) -> usize {
         self.offset
     }
 
+    #[inline(always)]
     pub fn advance(&mut self, num_bytes: usize) {
         self.offset += num_bytes;
     }
 
+    #[inline(always)]
     pub fn buffer(&self) -> &[u8] {
         &self.buffer[self.offset..]
     }

sstable/src/delta.rs

@@ -16,6 +16,8 @@ where W: io::Write
     block: Vec<u8>,
     write: CountingWriter<BufWriter<W>>,
     value_writer: TValueWriter,
+    // Only here to avoid allocations.
+    stateless_buffer: Vec<u8>,
 }
 
 impl<W, TValueWriter> DeltaWriter<W, TValueWriter>
@@ -28,6 +30,7 @@ where
             block: Vec::with_capacity(BLOCK_LEN * 2),
             write: CountingWriter::wrap(BufWriter::new(wrt)),
             value_writer: TValueWriter::default(),
+            stateless_buffer: Vec::new(),
         }
     }
 }
@@ -42,15 +45,16 @@ where
             return Ok(None);
         }
         let start_offset = self.write.written_bytes() as usize;
-        // TODO avoid buffer allocation
-        let mut buffer = Vec::new();
-        self.value_writer.serialize_block(&mut buffer);
+        let buffer: &mut Vec<u8> = &mut self.stateless_buffer;
+        self.value_writer.serialize_block(buffer);
+        self.value_writer.clear();
         let block_len = buffer.len() + self.block.len();
         self.write.write_all(&(block_len as u32).to_le_bytes())?;
         self.write.write_all(&buffer[..])?;
         self.write.write_all(&self.block[..])?;
         let end_offset = self.write.written_bytes() as usize;
         self.block.clear();
+        buffer.clear();
         Ok(Some(start_offset..end_offset))
     }
 
@@ -91,8 +95,7 @@ where
 
 pub struct DeltaReader<'a, TValueReader> {
     common_prefix_len: usize,
-    suffix_start: usize,
-    suffix_end: usize,
+    suffix_range: Range<usize>,
     value_reader: TValueReader,
     block_reader: BlockReader<'a>,
     idx: usize,
@@ -105,8 +108,7 @@ where TValueReader: value::ValueReader
         DeltaReader {
             idx: 0,
             common_prefix_len: 0,
-            suffix_start: 0,
-            suffix_end: 0,
+            suffix_range: 0..0,
             value_reader: TValueReader::default(),
             block_reader: BlockReader::new(Box::new(reader)),
         }
@@ -144,15 +146,14 @@ where TValueReader: value::ValueReader
     }
 
     fn read_delta_key(&mut self) -> bool {
-        if let Some((keep, add)) = self.read_keep_add() {
-            self.common_prefix_len = keep;
-            self.suffix_start = self.block_reader.offset();
-            self.suffix_end = self.suffix_start + add;
-            self.block_reader.advance(add);
-            true
-        } else {
-            false
-        }
+        let Some((keep, add)) = self.read_keep_add() else {
+            return false;
+        };
+        self.common_prefix_len = keep;
+        let suffix_start = self.block_reader.offset();
+        self.suffix_range = suffix_start..(suffix_start + add);
+        self.block_reader.advance(add);
+        true
     }
 
     pub fn advance(&mut self) -> io::Result<bool> {
@@ -172,15 +173,17 @@ where TValueReader: value::ValueReader
         Ok(true)
     }
 
+    #[inline(always)]
     pub fn common_prefix_len(&self) -> usize {
         self.common_prefix_len
     }
 
+    #[inline(always)]
     pub fn suffix(&self) -> &[u8] {
-        self.block_reader
-            .buffer_from_to(self.suffix_start, self.suffix_end)
+        self.block_reader.buffer_from_to(self.suffix_range.clone())
     }
 
+    #[inline(always)]
     pub fn value(&self) -> &TValueReader::Value {
         self.value_reader.value(self.idx)
     }
@@ -189,11 +192,11 @@ where TValueReader: value::ValueReader
 #[cfg(test)]
 mod tests {
     use super::DeltaReader;
-    use crate::value::U64MonotonicReader;
+    use crate::value::U64MonotonicValueReader;
 
     #[test]
     fn test_empty() {
-        let mut delta_reader: DeltaReader<U64MonotonicReader> = DeltaReader::empty();
+        let mut delta_reader: DeltaReader<U64MonotonicValueReader> = DeltaReader::empty();
         assert!(!delta_reader.advance().unwrap());
     }
 }

sstable/src/dictionary.rs

@@ -11,12 +11,25 @@ use tantivy_fst::Automaton;
 use crate::streamer::{Streamer, StreamerBuilder};
 use crate::{BlockAddr, DeltaReader, Reader, SSTable, SSTableIndex, TermOrdinal};
 
-/// The term dictionary contains all of the terms in
-/// `tantivy index` in a sorted manner.
+/// An SSTable is a sorted map that associates sorted `&[u8]` keys
+/// to any kind of typed values.
 ///
-/// The `Fst` crate is used to associate terms to their
-/// respective `TermOrdinal`. The `TermInfoStore` then makes it
-/// possible to fetch the associated `TermInfo`.
+/// The SSTable is organized in blocks.
+/// In each block, keys and values are encoded separately.
+///
+/// The keys are encoded using incremental encoding.
+/// The values on the other hand, are encoded according to a value-specific
+/// codec defined in the TSSTable generic argument.
+///
+/// Finally, an index is joined to the Dictionary to make it possible,
+/// given a key to identify which block contains this key.
+///
+/// The codec was designed in such a way that the sstable
+/// reader is not aware of block, and yet can read any sequence of blocks,
+/// as long as the slice of bytes it is given starts and stops at
+/// block boundary.
+///
+/// (See also README.md)
 pub struct Dictionary<TSSTable: SSTable> {
     pub sstable_slice: FileSlice,
     pub sstable_index: SSTableIndex,
@@ -62,6 +75,23 @@ impl<TSSTable: SSTable> Dictionary<TSSTable> {
         Ok(TSSTable::delta_reader(data))
     }
 
+    /// This function returns a file slice covering a set of sstable blocks
+    /// that include the key range passed in arguments.
+    ///
+    /// It works by identifying
+    /// - `first_block`: the block containing the start boudary key
+    /// - `last_block`: the block containing the end boundary key.
+    ///
+    /// And then returning the range that spans over all blocks between.
+    /// and including first_block and last_block, aka:
+    /// `[first_block.start_offset .. last_block.end_offset)`
+    ///
+    /// Technically this function does not provide the tightest fit, as
+    /// for simplification, it treats the start bound of the `key_range`
+    /// as if it was inclusive, even if it is exclusive.
+    /// On the rare edge case where a user asks for `(start_key, end_key]`
+    /// and `start_key` happens to be the last key of a block, we return a
+    /// slice that is the first block was not necessary.
     fn file_slice_for_range(&self, key_range: impl RangeBounds<[u8]>) -> FileSlice {
         let start_bound: Bound<usize> = match key_range.start_bound() {
             Bound::Included(key) | Bound::Excluded(key) => {

sstable/src/lib.rs

@@ -20,13 +20,15 @@ mod block_reader;
 pub use self::block_reader::BlockReader;
 pub use self::delta::{DeltaReader, DeltaWriter};
 pub use self::merge::VoidMerge;
-use self::value::{U64MonotonicReader, U64MonotonicWriter, ValueReader, ValueWriter};
-use crate::value::{RangeReader, RangeWriter};
+use self::value::{U64MonotonicValueReader, U64MonotonicValueWriter, ValueReader, ValueWriter};
+use crate::value::{RangeValueReader, RangeValueWriter};
 
 pub type TermOrdinal = u64;
 
 const DEFAULT_KEY_CAPACITY: usize = 50;
 
+/// Given two byte string returns the length of
+/// the longest common prefix.
 fn common_prefix_len(left: &[u8], right: &[u8]) -> usize {
     left.iter()
         .cloned()
@@ -38,6 +40,8 @@ fn common_prefix_len(left: &[u8], right: &[u8]) -> usize {
 #[derive(Debug, Copy, Clone)]
 pub struct SSTableDataCorruption;
 
+/// SSTable makes it possible to read and write
+/// sstables with typed values.
 pub trait SSTable: Sized {
     type Value: Clone;
     type ValueReader: ValueReader<Value = Self::Value>;
@@ -47,14 +51,8 @@ pub trait SSTable: Sized {
         DeltaWriter::new(write)
     }
 
-    fn writer<W: io::Write>(write: W) -> Writer<W, Self::ValueWriter> {
-        Writer {
-            previous_key: Vec::with_capacity(DEFAULT_KEY_CAPACITY),
-            num_terms: 0u64,
-            index_builder: SSTableIndexBuilder::default(),
-            delta_writer: Self::delta_writer(write),
-            first_ordinal_of_the_block: 0u64,
-        }
+    fn writer<W: io::Write>(wrt: W) -> Writer<W, Self::ValueWriter> {
+        Writer::new(wrt)
     }
 
     fn delta_reader<'a, R: io::Read + 'a>(reader: R) -> DeltaReader<'a, Self::ValueReader> {
@@ -89,32 +87,47 @@ pub struct VoidSSTable;
 
 impl SSTable for VoidSSTable {
     type Value = ();
-    type ValueReader = value::VoidReader;
-    type ValueWriter = value::VoidWriter;
+    type ValueReader = value::VoidValueReader;
+    type ValueWriter = value::VoidValueWriter;
 }
 
+/// SSTable associated keys to u64
+/// sorted in order.
+///
+/// In other words, two keys `k1` and `k2`
+/// such that `k1` <= `k2`, are required to observe
+/// `range_sstable[k1] <= range_sstable[k2]`.
 #[allow(dead_code)]
-pub struct SSTableMonotonicU64;
+pub struct MonotonicU64SSTable;
 
-impl SSTable for SSTableMonotonicU64 {
+impl SSTable for MonotonicU64SSTable {
     type Value = u64;
 
-    type ValueReader = U64MonotonicReader;
+    type ValueReader = U64MonotonicValueReader;
 
-    type ValueWriter = U64MonotonicWriter;
+    type ValueWriter = U64MonotonicValueWriter;
 }
 
-/// Retpresent
-pub struct SSTableRange;
+/// SSTable associating keys to ranges.
+/// The range are required to partition the
+/// space.
+///
+/// In other words, two consecutive keys `k1` and `k2`
+/// are required to observe
+/// `range_sstable[k1].end == range_sstable[k2].start`.
+///
+/// The first range is not required to start at `0`.
+pub struct RangeSSTable;
 
-impl SSTable for SSTableRange {
+impl SSTable for RangeSSTable {
     type Value = Range<u64>;
 
-    type ValueReader = RangeReader;
+    type ValueReader = RangeValueReader;
 
-    type ValueWriter = RangeWriter;
+    type ValueWriter = RangeValueWriter;
 }
 
+/// SSTable reader.
 pub struct Reader<'a, TValueReader> {
     key: Vec<u8>,
     delta_reader: DeltaReader<'a, TValueReader>,
@@ -135,16 +148,19 @@ where TValueReader: ValueReader
         Ok(true)
     }
 
+    #[inline(always)]
     pub fn key(&self) -> &[u8] {
         &self.key
     }
 
+    #[inline(always)]
     pub fn value(&self) -> &TValueReader::Value {
         self.delta_reader.value()
     }
 }
 
 impl<'a, TValueReader> AsRef<[u8]> for Reader<'a, TValueReader> {
+    #[inline(always)]
     fn as_ref(&self) -> &[u8] {
         &self.key
     }
@@ -165,21 +181,54 @@ where
     W: io::Write,
     TValueWriter: value::ValueWriter,
 {
+    /// Use `Self::new`. This method only exists to match its
+    /// equivalent in fst.
+    /// TODO remove this function. (See Issue #1727)
+    #[doc(hidden)]
     pub fn create(wrt: W) -> io::Result<Self> {
-        Ok(Writer {
+        Ok(Self::new(wrt))
+    }
+
+    /// Creates a new `TermDictionaryBuilder`.
+    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,
-        })
+        }
     }
 
+    /// Returns the last inserted key.
+    /// If no key has been inserted yet, or the block was just
+    /// flushed, this function returns "".
     #[inline(always)]
-    pub(crate) fn current_key(&self) -> &[u8] {
+    pub(crate) fn last_inserted_key(&self) -> &[u8] {
         &self.previous_key[..]
     }
 
+    /// Inserts a `(key, value)` pair in the term dictionary.
+    /// Keys have to be inserted in order.
+    ///
+    /// # Panics
+    ///
+    /// Will panics if keys are inserted in an invalid order.
+    #[inline]
+    pub fn insert<K: AsRef<[u8]>>(
+        &mut self,
+        key: K,
+        value: &TValueWriter::Value,
+    ) -> io::Result<()> {
+        self.insert_key(key.as_ref())?;
+        self.insert_value(value)?;
+        Ok(())
+    }
+
+    /// # Warning
+    ///
+    /// Horribly dangerous internal API. See `.insert(...)`.
+    #[doc(hidden)]
     #[inline]
     pub fn insert_key(&mut self, key: &[u8]) -> io::Result<()> {
         // If this is the first key in the block, we use it to
@@ -204,17 +253,10 @@ where
         Ok(())
     }
 
-    #[inline]
-    pub fn insert<K: AsRef<[u8]>>(
-        &mut self,
-        key: K,
-        value: &TValueWriter::Value,
-    ) -> io::Result<()> {
-        self.insert_key(key.as_ref())?;
-        self.insert_value(value)?;
-        Ok(())
-    }
-
+    /// # Warning
+    ///
+    /// Horribly dangerous internal API. See `.insert(...)`.
+    #[doc(hidden)]
     #[inline]
     pub fn insert_value(&mut self, value: &TValueWriter::Value) -> io::Result<()> {
         self.delta_writer.write_value(value);
@@ -256,11 +298,23 @@ where
         Ok(wrt.into_inner()?)
     }
 }
+
+impl<TValueWriter> Writer<Vec<u8>, TValueWriter>
+where TValueWriter: value::ValueWriter
+{
+    #[inline]
+    pub fn insert_cannot_fail<K: AsRef<[u8]>>(&mut self, key: K, value: &TValueWriter::Value) {
+        self.insert(key, value)
+            .expect("SSTable over a Vec should never fail");
+    }
+}
+
 #[cfg(test)]
 mod test {
     use std::io;
+    use std::ops::Bound;
 
-    use super::{common_prefix_len, SSTable, SSTableMonotonicU64, VoidMerge, VoidSSTable};
+    use super::{common_prefix_len, MonotonicU64SSTable, SSTable, VoidMerge, VoidSSTable};
 
     fn aux_test_common_prefix_len(left: &str, right: &str, expect_len: usize) {
         assert_eq!(
@@ -369,8 +423,11 @@ mod test {
         let mut buffer = Vec::new();
         {
             let mut writer = VoidSSTable::writer(&mut buffer);
+            assert_eq!(writer.last_inserted_key(), b"");
             writer.insert(b"abcd", &()).unwrap();
+            assert_eq!(writer.last_inserted_key(), b"abcd");
             writer.insert(b"abe", &()).unwrap();
+            assert_eq!(writer.last_inserted_key(), b"abe");
             writer.finish().unwrap();
         }
         let mut output = Vec::new();
@@ -381,12 +438,12 @@ mod test {
     #[test]
     fn test_sstable_u64() -> io::Result<()> {
         let mut buffer = Vec::new();
-        let mut writer = SSTableMonotonicU64::writer(&mut buffer);
+        let mut writer = MonotonicU64SSTable::writer(&mut buffer);
         writer.insert(b"abcd", &1u64)?;
         writer.insert(b"abe", &4u64)?;
         writer.insert(b"gogo", &4324234234234234u64)?;
         writer.finish()?;
-        let mut reader = SSTableMonotonicU64::reader(&buffer[..]);
+        let mut reader = MonotonicU64SSTable::reader(&buffer[..]);
         assert!(reader.advance()?);
         assert_eq!(reader.key(), b"abcd");
         assert_eq!(reader.value(), &1u64);
@@ -402,7 +459,72 @@ mod test {
 
     #[test]
     fn test_sstable_empty() {
-        let mut sstable_range_empty = crate::SSTableRange::create_empty_reader();
+        let mut sstable_range_empty = crate::RangeSSTable::create_empty_reader();
         assert!(!sstable_range_empty.advance().unwrap());
     }
+
+    use common::file_slice::FileSlice;
+    use proptest::prelude::*;
+
+    use crate::Dictionary;
+
+    fn bound_strategy() -> impl Strategy<Value = Bound<String>> {
+        prop_oneof![
+            Just(Bound::<String>::Unbounded),
+            "[a-d]*".prop_map(|key| Bound::Included(key)),
+            "[a-d]*".prop_map(|key| Bound::Excluded(key)),
+        ]
+    }
+
+    fn extract_key(bound: Bound<&String>) -> Option<&str> {
+        match bound.as_ref() {
+            Bound::Included(key) => Some(key.as_str()),
+            Bound::Excluded(key) => Some(key.as_str()),
+            Bound::Unbounded => None,
+        }
+    }
+
+    fn bounds_strategy() -> impl Strategy<Value = (Bound<String>, Bound<String>)> {
+        (bound_strategy(), bound_strategy()).prop_filter(
+            "Lower bound <= Upper bound",
+            |(left, right)| match (extract_key(left.as_ref()), extract_key(right.as_ref())) {
+                (None, _) => true,
+                (_, None) => true,
+                (left, right) => left <= right,
+            },
+        )
+    }
+
+    proptest! {
+        #[test]
+        fn test_prop_test_ranges(words in prop::collection::btree_set("[a-d]*", 1..100),
+            (lower_bound, upper_bound) in bounds_strategy(),
+        ) {
+            // TODO tweak block size.
+            let mut builder = Dictionary::<VoidSSTable>::builder(Vec::new()).unwrap();
+            for word in &words {
+                builder.insert(word.as_bytes(), &()).unwrap();
+            }
+            let buffer: Vec<u8> = builder.finish().unwrap();
+            let dictionary: Dictionary<VoidSSTable> = Dictionary::open(FileSlice::from(buffer)).unwrap();
+            let mut range_builder = dictionary.range();
+            range_builder = match lower_bound.as_ref() {
+                Bound::Included(key) => range_builder.ge(key.as_bytes()),
+                Bound::Excluded(key) => range_builder.gt(key.as_bytes()),
+                Bound::Unbounded => range_builder,
+            };
+            range_builder = match upper_bound.as_ref() {
+                Bound::Included(key) => range_builder.le(key.as_bytes()),
+                Bound::Excluded(key) => range_builder.lt(key.as_bytes()),
+                Bound::Unbounded => range_builder,
+            };
+            let mut stream = range_builder.into_stream().unwrap();
+            let mut btree_set_range = words.range((lower_bound, upper_bound));
+            while stream.advance() {
+                let val = btree_set_range.next().unwrap();
+                assert_eq!(val.as_bytes(), stream.key());
+            }
+            assert!(btree_set_range.next().is_none());
+        }
+    }
 }

sstable/src/merge/heap_merge.rs

@@ -53,7 +53,7 @@ pub fn merge_sstable<SST: SSTable, W: io::Write, M: ValueMerger<SST::Value>>(
         }
         for _ in 0..len - 1 {
             if let Some(mut head) = heap.peek_mut() {
-                if head.0.key() == writer.current_key() {
+                if head.0.key() == writer.last_inserted_key() {
                     value_merger.add(head.0.value());
                     if !head.0.advance()? {
                         PeekMut::pop(head);

sstable/src/merge/mod.rs

@@ -71,7 +71,7 @@ mod tests {
     use std::collections::{BTreeMap, BTreeSet};
     use std::str;
 
-    use super::super::{SSTable, SSTableMonotonicU64, VoidSSTable};
+    use super::super::{MonotonicU64SSTable, SSTable, VoidSSTable};
     use super::{U64Merge, VoidMerge};
 
     fn write_sstable(keys: &[&'static str]) -> Vec<u8> {
@@ -89,7 +89,7 @@ mod tests {
     fn write_sstable_u64(keys: &[(&'static str, u64)]) -> Vec<u8> {
         let mut buffer: Vec<u8> = vec![];
         {
-            let mut sstable_writer = SSTableMonotonicU64::writer(&mut buffer);
+            let mut sstable_writer = MonotonicU64SSTable::writer(&mut buffer);
             for (key, val) in keys {
                 assert!(sstable_writer.insert(key.as_bytes(), val).is_ok());
             }
@@ -132,8 +132,8 @@ mod tests {
             }
         }
         let mut w = Vec::new();
-        assert!(SSTableMonotonicU64::merge(sstables_ref, &mut w, U64Merge).is_ok());
-        let mut reader = SSTableMonotonicU64::reader(&w[..]);
+        assert!(MonotonicU64SSTable::merge(sstables_ref, &mut w, U64Merge).is_ok());
+        let mut reader = MonotonicU64SSTable::reader(&w[..]);
         for (k, v) in merged {
             assert!(reader.advance().unwrap());
             assert_eq!(reader.key(), k.as_bytes());

sstable/src/sstable_index.rs

@@ -16,16 +16,9 @@ impl SSTableIndex {
     }
 
     pub fn search_block(&self, key: &[u8]) -> Option<BlockAddr> {
-        self.search_block_from(key).next()
-    }
-
-    pub fn search_block_from<'key, 'slf: 'key>(
-        &'slf self,
-        key: &'key [u8],
-    ) -> impl Iterator<Item = BlockAddr> + Clone + 'key {
         self.blocks
             .iter()
-            .skip_while(|block| &block.last_key_or_greater[..] < key)
+            .find(|block| &block.last_key_or_greater[..] >= key)
             .map(|block| block.block_addr.clone())
     }
 }

sstable/src/streamer.rs

@@ -211,10 +211,10 @@ mod tests {
 
     use common::OwnedBytes;
 
-    use crate::{Dictionary, SSTableMonotonicU64};
+    use crate::{Dictionary, MonotonicU64SSTable};
 
-    fn create_test_dictionary() -> io::Result<Dictionary<SSTableMonotonicU64>> {
-        let mut dict_builder = Dictionary::<SSTableMonotonicU64>::builder(Vec::new())?;
+    fn create_test_dictionary() -> io::Result<Dictionary<MonotonicU64SSTable>> {
+        let mut dict_builder = Dictionary::<MonotonicU64SSTable>::builder(Vec::new())?;
         dict_builder.insert(b"abaisance", &0)?;
         dict_builder.insert(b"abalation", &1)?;
         dict_builder.insert(b"abalienate", &2)?;

sstable/src/value/mod.rs

@@ -20,24 +20,30 @@ pub trait ValueReader: Default {
     fn load(&mut self, data: &[u8]) -> io::Result<usize>;
 }
 
+/// `ValueWriter` is a trait to make it possible to write blocks
+/// of value.
 pub trait ValueWriter: Default {
     /// Type of the value being written.
     type Value;
 
     /// Records a new value.
     /// This method usually just accumulates data in a `Vec`,
-    /// only to be serialized on the call to `ValueWriter::write_block`.
+    /// only to be serialized on the call to `ValueWriter::serialize_block`.
     fn write(&mut self, val: &Self::Value);
 
     /// Serializes the accumulated values into the output buffer.
-    fn serialize_block(&mut self, output: &mut Vec<u8>);
+    fn serialize_block(&self, output: &mut Vec<u8>);
+
+    /// Clears the `ValueWriter`. After a call to clear, the `ValueWriter`
+    /// should behave like a fresh `ValueWriter::default()`.
+    fn clear(&mut self);
 }
 
-pub use range::{RangeReader, RangeWriter};
-pub use u64_monotonic::{U64MonotonicReader, U64MonotonicWriter};
-pub use void::{VoidReader, VoidWriter};
+pub use range::{RangeValueReader, RangeValueWriter};
+pub use u64_monotonic::{U64MonotonicValueReader, U64MonotonicValueWriter};
+pub use void::{VoidValueReader, VoidValueWriter};
 
-fn deserialize_u64(data: &mut &[u8]) -> u64 {
+fn deserialize_vint_u64(data: &mut &[u8]) -> u64 {
     let (num_bytes, val) = super::vint::deserialize_read(data);
     *data = &data[num_bytes..];
     val
@@ -63,6 +69,7 @@ pub(crate) mod tests {
                 writer.write(value);
             }
             writer.serialize_block(&mut buffer);
+            writer.clear();
         }
         let data_len = buffer.len();
         buffer.extend_from_slice(&b"extradata"[..]);

sstable/src/value/range.rs

@@ -1,16 +1,18 @@
 use std::io;
 use std::ops::Range;
 
-use crate::value::{deserialize_u64, ValueReader, ValueWriter};
+use crate::value::{deserialize_vint_u64, ValueReader, ValueWriter};
 
+/// See module comment.
 #[derive(Default)]
-pub struct RangeReader {
+pub struct RangeValueReader {
     vals: Vec<Range<u64>>,
 }
 
-impl ValueReader for RangeReader {
+impl ValueReader for RangeValueReader {
     type Value = Range<u64>;
 
+    #[inline(always)]
     fn value(&self, idx: usize) -> &Range<u64> {
         &self.vals[idx]
     }
@@ -18,11 +20,11 @@ impl ValueReader for RangeReader {
     fn load(&mut self, mut data: &[u8]) -> io::Result<usize> {
         self.vals.clear();
         let original_num_bytes = data.len();
-        let len = deserialize_u64(&mut data) as usize;
+        let len = deserialize_vint_u64(&mut data) as usize;
         if len != 0 {
-            let mut prev_val = deserialize_u64(&mut data);
+            let mut prev_val = deserialize_vint_u64(&mut data);
             for _ in 1..len {
-                let next_val = prev_val + deserialize_u64(&mut data);
+                let next_val = prev_val + deserialize_vint_u64(&mut data);
                 self.vals.push(prev_val..next_val);
                 prev_val = next_val;
             }
@@ -31,12 +33,23 @@ impl ValueReader for RangeReader {
     }
 }
 
+/// Range writer. The range are required to partition the
+/// space.
+///
+/// In other words, two consecutive keys `k1` and `k2`
+/// are required to observe
+/// `range_sstable[k1].end == range_sstable[k2].start`.
+///
+/// The writer will panic if the inserted value do not follow
+/// this property.
+///
+/// The first range is not required to start at `0`.
 #[derive(Default)]
-pub struct RangeWriter {
+pub struct RangeValueWriter {
     vals: Vec<u64>,
 }
 
-impl ValueWriter for RangeWriter {
+impl ValueWriter for RangeValueWriter {
     type Value = Range<u64>;
 
     fn write(&mut self, val: &Range<u64>) {
@@ -49,7 +62,7 @@ impl ValueWriter for RangeWriter {
         }
     }
 
-    fn serialize_block(&mut self, writer: &mut Vec<u8>) {
+    fn serialize_block(&self, writer: &mut Vec<u8>) {
         let mut prev_val = 0u64;
         crate::vint::serialize_into_vec(self.vals.len() as u64, writer);
         for &val in &self.vals {
@@ -57,6 +70,9 @@ impl ValueWriter for RangeWriter {
             crate::vint::serialize_into_vec(delta, writer);
             prev_val = val;
         }
+    }
+
+    fn clear(&mut self) {
         self.vals.clear();
     }
 }
@@ -67,17 +83,19 @@ mod tests {
 
     #[test]
     fn test_range_reader_writer() {
-        crate::value::tests::test_value_reader_writer::<_, RangeReader, RangeWriter>(&[]);
-        crate::value::tests::test_value_reader_writer::<_, RangeReader, RangeWriter>(&[0..3]);
-        crate::value::tests::test_value_reader_writer::<_, RangeReader, RangeWriter>(&[
+        crate::value::tests::test_value_reader_writer::<_, RangeValueReader, RangeValueWriter>(&[]);
+        crate::value::tests::test_value_reader_writer::<_, RangeValueReader, RangeValueWriter>(&[
+            0..3,
+        ]);
+        crate::value::tests::test_value_reader_writer::<_, RangeValueReader, RangeValueWriter>(&[
             0..3,
             3..10,
         ]);
-        crate::value::tests::test_value_reader_writer::<_, RangeReader, RangeWriter>(&[
+        crate::value::tests::test_value_reader_writer::<_, RangeValueReader, RangeValueWriter>(&[
             0..0,
             0..10,
         ]);
-        crate::value::tests::test_value_reader_writer::<_, RangeReader, RangeWriter>(&[
+        crate::value::tests::test_value_reader_writer::<_, RangeValueReader, RangeValueWriter>(&[
             100..110,
             110..121,
             121..1250,
@@ -87,7 +105,7 @@ mod tests {
     #[test]
     #[should_panic]
     fn test_range_reader_writer_panics() {
-        crate::value::tests::test_value_reader_writer::<_, RangeReader, RangeWriter>(&[
+        crate::value::tests::test_value_reader_writer::<_, RangeValueReader, RangeValueWriter>(&[
             1..3,
             4..10,
         ]);

sstable/src/value/u64_monotonic.rs

@@ -1,27 +1,28 @@
 use std::io;
 
-use crate::value::{deserialize_u64, ValueReader, ValueWriter};
+use crate::value::{deserialize_vint_u64, ValueReader, ValueWriter};
 use crate::vint;
 
 #[derive(Default)]
-pub struct U64MonotonicReader {
+pub struct U64MonotonicValueReader {
     vals: Vec<u64>,
 }
 
-impl ValueReader for U64MonotonicReader {
+impl ValueReader for U64MonotonicValueReader {
     type Value = u64;
 
+    #[inline(always)]
     fn value(&self, idx: usize) -> &Self::Value {
         &self.vals[idx]
     }
 
     fn load(&mut self, mut data: &[u8]) -> io::Result<usize> {
         let original_num_bytes = data.len();
-        let num_vals = deserialize_u64(&mut data) as usize;
+        let num_vals = deserialize_vint_u64(&mut data) as usize;
         self.vals.clear();
         let mut prev_val = 0u64;
         for _ in 0..num_vals {
-            let delta = deserialize_u64(&mut data);
+            let delta = deserialize_vint_u64(&mut data);
             let val = prev_val + delta;
             self.vals.push(val);
             prev_val = val;
@@ -31,18 +32,18 @@ impl ValueReader for U64MonotonicReader {
 }
 
 #[derive(Default)]
-pub struct U64MonotonicWriter {
+pub struct U64MonotonicValueWriter {
     vals: Vec<u64>,
 }
 
-impl ValueWriter for U64MonotonicWriter {
+impl ValueWriter for U64MonotonicValueWriter {
     type Value = u64;
 
     fn write(&mut self, val: &Self::Value) {
         self.vals.push(*val);
     }
 
-    fn serialize_block(&mut self, output: &mut Vec<u8>) {
+    fn serialize_block(&self, output: &mut Vec<u8>) {
         let mut prev_val = 0u64;
         vint::serialize_into_vec(self.vals.len() as u64, output);
         for &val in &self.vals {
@@ -50,6 +51,9 @@ impl ValueWriter for U64MonotonicWriter {
             vint::serialize_into_vec(delta, output);
             prev_val = val;
         }
+    }
+
+    fn clear(&mut self) {
         self.vals.clear();
     }
 }
@@ -60,14 +64,20 @@ mod tests {
 
     #[test]
     fn test_u64_monotonic_reader_writer() {
-        crate::value::tests::test_value_reader_writer::<_, U64MonotonicReader, U64MonotonicWriter>(
-            &[],
-        );
-        crate::value::tests::test_value_reader_writer::<_, U64MonotonicReader, U64MonotonicWriter>(
-            &[5],
-        );
-        crate::value::tests::test_value_reader_writer::<_, U64MonotonicReader, U64MonotonicWriter>(
-            &[1u64, 30u64],
-        );
+        crate::value::tests::test_value_reader_writer::<
+            _,
+            U64MonotonicValueReader,
+            U64MonotonicValueWriter,
+        >(&[]);
+        crate::value::tests::test_value_reader_writer::<
+            _,
+            U64MonotonicValueReader,
+            U64MonotonicValueWriter,
+        >(&[5]);
+        crate::value::tests::test_value_reader_writer::<
+            _,
+            U64MonotonicValueReader,
+            U64MonotonicValueWriter,
+        >(&[1u64, 30u64]);
     }
 }

sstable/src/value/void.rs

@@ -3,11 +3,12 @@ use std::io;
 use crate::value::{ValueReader, ValueWriter};
 
 #[derive(Default)]
-pub struct VoidReader;
+pub struct VoidValueReader;
 
-impl ValueReader for VoidReader {
+impl ValueReader for VoidValueReader {
     type Value = ();
 
+    #[inline(always)]
     fn value(&self, _idx: usize) -> &() {
         &()
     }
@@ -18,14 +19,16 @@ impl ValueReader for VoidReader {
 }
 
 #[derive(Default)]
-pub struct VoidWriter;
+pub struct VoidValueWriter;
 
-impl ValueWriter for VoidWriter {
+impl ValueWriter for VoidValueWriter {
     type Value = ();
 
     fn write(&mut self, _val: &()) {}
 
-    fn serialize_block(&mut self, _output: &mut Vec<u8>) {}
+    fn serialize_block(&self, _output: &mut Vec<u8>) {}
+
+    fn clear(&mut self) {}
 }
 
 #[cfg(test)]
@@ -34,8 +37,12 @@ mod tests {
 
     #[test]
     fn test_range_reader_writer() {
-        crate::value::tests::test_value_reader_writer::<_, VoidReader, VoidWriter>(&[]);
-        crate::value::tests::test_value_reader_writer::<_, VoidReader, VoidWriter>(&[()]);
-        crate::value::tests::test_value_reader_writer::<_, VoidReader, VoidWriter>(&[(), (), ()]);
+        crate::value::tests::test_value_reader_writer::<_, VoidValueReader, VoidValueWriter>(&[]);
+        crate::value::tests::test_value_reader_writer::<_, VoidValueReader, VoidValueWriter>(&[()]);
+        crate::value::tests::test_value_reader_writer::<_, VoidValueReader, VoidValueWriter>(&[
+            (),
+            (),
+            (),
+        ]);
     }
 }

stacker/Cargo.toml

@@ -2,6 +2,7 @@
 name = "tantivy-stacker"
 version = "0.1.0"
 edition = "2021"
+license = "MIT"
 
 [dependencies]
 murmurhash32 = "0.2"