try with custom Cow<str>

Cargo.toml

@@ -61,6 +61,7 @@ measure_time = "0.8.2"
 ciborium = { version = "0.2", optional = true}
 async-trait = "0.1.53"
 arc-swap = "1.5.0"
+yoke = { version = "0.6.2", features = ["derive"] }
 
 [target.'cfg(windows)'.dependencies]
 winapi = "0.3.9"

benches/index-bench.rs

@@ -1,116 +1,159 @@
 use criterion::{criterion_group, criterion_main, Criterion};
+use itertools::Itertools;
 use pprof::criterion::{Output, PProfProfiler};
-use tantivy::schema::{INDEXED, STORED, STRING, TEXT};
-use tantivy::Index;
+use serde_json::{self, Value as JsonValue};
+use tantivy::directory::RamDirectory;
+use tantivy::schema::{
+    FieldValue, TextFieldIndexing, TextOptions, Value, INDEXED, STORED, STRING, TEXT,
+};
+use tantivy::{Document, Index, IndexBuilder};
 
 const HDFS_LOGS: &str = include_str!("hdfs.json");
-const NUM_REPEATS: usize = 2;
+const NUM_REPEATS: usize = 20;
 
 pub fn hdfs_index_benchmark(c: &mut Criterion) {
-    let schema = {
-        let mut schema_builder = tantivy::schema::SchemaBuilder::new();
-        schema_builder.add_u64_field("timestamp", INDEXED);
-        schema_builder.add_text_field("body", TEXT);
-        schema_builder.add_text_field("severity", STRING);
-        schema_builder.build()
-    };
-    let schema_with_store = {
-        let mut schema_builder = tantivy::schema::SchemaBuilder::new();
-        schema_builder.add_u64_field("timestamp", INDEXED | STORED);
-        schema_builder.add_text_field("body", TEXT | STORED);
-        schema_builder.add_text_field("severity", STRING | STORED);
-        schema_builder.build()
-    };
-    let dynamic_schema = {
-        let mut schema_builder = tantivy::schema::SchemaBuilder::new();
-        schema_builder.add_json_field("json", TEXT);
-        schema_builder.build()
-    };
+    let mut schema_builder = tantivy::schema::SchemaBuilder::new();
+    let text_indexing_options = TextFieldIndexing::default()
+        .set_tokenizer("default")
+        .set_fieldnorms(false)
+        .set_index_option(tantivy::schema::IndexRecordOption::WithFreqsAndPositions);
+    let mut text_options = TextOptions::default().set_indexing_options(text_indexing_options);
+    let text_field = schema_builder.add_text_field("body", text_options);
+    let schema = schema_builder.build();
+
+    // prepare doc
+    let mut documents_no_array = Vec::new();
+    let mut documents_with_array = Vec::new();
+    for doc_json in HDFS_LOGS.trim().split("\n") {
+        let json_obj: serde_json::Map<String, JsonValue> = serde_json::from_str(doc_json).unwrap();
+        let text = json_obj.get("body").unwrap().as_str().unwrap();
+        let mut doc_no_array = Document::new();
+        doc_no_array.add_text(text_field, text);
+        documents_no_array.push(doc_no_array);
+        let mut doc_with_array = Document::new();
+        doc_with_array.add_borrowed_values(text.to_owned(), |text| {
+            text.split(' ')
+                .map(|text| FieldValue::new(text_field, text.into()))
+                .collect()
+        });
+        documents_with_array.push(doc_with_array);
+    }
 
     let mut group = c.benchmark_group("index-hdfs");
     group.sample_size(20);
     group.bench_function("index-hdfs-no-commit", |b| {
         b.iter(|| {
-            let index = Index::create_in_ram(schema.clone());
-            let index_writer = index.writer_with_num_threads(1, 100_000_000).unwrap();
+            let ram_directory = RamDirectory::create();
+            let mut index_writer = IndexBuilder::new()
+                .schema(schema.clone())
+                .single_segment_index_writer(ram_directory, 100_000_000)
+                .unwrap();
             for _ in 0..NUM_REPEATS {
-                for doc_json in HDFS_LOGS.trim().split("\n") {
-                    let doc = schema.parse_document(doc_json).unwrap();
+                let documents_cloned = documents_no_array.clone();
+                for doc in documents_cloned {
                     index_writer.add_document(doc).unwrap();
                 }
             }
         })
     });
-    group.bench_function("index-hdfs-with-commit", |b| {
+    group.bench_function("index-hdfs-with-array-no-commit", |b| {
         b.iter(|| {
-            let index = Index::create_in_ram(schema.clone());
-            let mut index_writer = index.writer_with_num_threads(1, 100_000_000).unwrap();
+            let ram_directory = RamDirectory::create();
+            let mut index_writer = IndexBuilder::new()
+                .schema(schema.clone())
+                .single_segment_index_writer(ram_directory, 100_000_000)
+                .unwrap();
             for _ in 0..NUM_REPEATS {
-                for doc_json in HDFS_LOGS.trim().split("\n") {
-                    let doc = schema.parse_document(doc_json).unwrap();
-                    index_writer.add_document(doc).unwrap();
-                }
-            }
-            index_writer.commit().unwrap();
-        })
-    });
-    group.bench_function("index-hdfs-no-commit-with-docstore", |b| {
-        b.iter(|| {
-            let index = Index::create_in_ram(schema_with_store.clone());
-            let index_writer = index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for _ in 0..NUM_REPEATS {
-                for doc_json in HDFS_LOGS.trim().split("\n") {
-                    let doc = schema.parse_document(doc_json).unwrap();
+                let documents_with_array_cloned = documents_with_array.clone();
+                for doc in documents_with_array_cloned {
                     index_writer.add_document(doc).unwrap();
                 }
             }
         })
     });
-    group.bench_function("index-hdfs-with-commit-with-docstore", |b| {
-        b.iter(|| {
-            let index = Index::create_in_ram(schema_with_store.clone());
-            let mut index_writer = index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for _ in 0..NUM_REPEATS {
-                for doc_json in HDFS_LOGS.trim().split("\n") {
-                    let doc = schema.parse_document(doc_json).unwrap();
-                    index_writer.add_document(doc).unwrap();
-                }
-            }
-            index_writer.commit().unwrap();
-        })
-    });
-    group.bench_function("index-hdfs-no-commit-json-without-docstore", |b| {
-        b.iter(|| {
-            let index = Index::create_in_ram(dynamic_schema.clone());
-            let json_field = dynamic_schema.get_field("json").unwrap();
-            let mut index_writer = index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for _ in 0..NUM_REPEATS {
-                for doc_json in HDFS_LOGS.trim().split("\n") {
-                    let json_val: serde_json::Map<String, serde_json::Value> =
-                        serde_json::from_str(doc_json).unwrap();
-                    let doc = tantivy::doc!(json_field=>json_val);
-                    index_writer.add_document(doc).unwrap();
-                }
-            }
-            index_writer.commit().unwrap();
-        })
-    });
-    group.bench_function("index-hdfs-with-commit-json-without-docstore", |b| {
-        b.iter(|| {
-            let index = Index::create_in_ram(dynamic_schema.clone());
-            let json_field = dynamic_schema.get_field("json").unwrap();
-            let mut index_writer = index.writer_with_num_threads(1, 100_000_000).unwrap();
-            for _ in 0..NUM_REPEATS {
-                for doc_json in HDFS_LOGS.trim().split("\n") {
-                    let json_val: serde_json::Map<String, serde_json::Value> =
-                        serde_json::from_str(doc_json).unwrap();
-                    let doc = tantivy::doc!(json_field=>json_val);
-                    index_writer.add_document(doc).unwrap();
-                }
-            }
-            index_writer.commit().unwrap();
-        })
-    });
+    // group.bench_function("index-hdfs-with-commit", |b| {
+    //     b.iter(|| {
+    //         let ram_directory = RamDirectory::create();
+    //         let mut index_writer = IndexBuilder::new()
+    //             .schema(schema.clone())
+    //             .single_segment_index_writer(ram_directory, 100_000_000)
+    //             .unwrap();
+    //         for _ in 0..NUM_REPEATS {
+    //             for doc_json in HDFS_LOGS.trim().split("\n") {
+    //                 let doc = schema.parse_document(doc_json).unwrap();
+    //                 index_writer.add_document(doc).unwrap();
+    //             }
+    //         }
+    //         index_writer.commit().unwrap();
+    //     })
+    // });
+    // group.bench_function("index-hdfs-no-commit-with-docstore", |b| {
+    //     b.iter(|| {
+    //         let ram_directory = RamDirectory::create();
+    //         let mut index_writer = IndexBuilder::new()
+    //             .schema(schema.clone())
+    //             .single_segment_index_writer(ram_directory, 100_000_000)
+    //             .unwrap();
+    //         for _ in 0..NUM_REPEATS {
+    //             for doc_json in HDFS_LOGS.trim().split("\n") {
+    //                 let doc = schema.parse_document(doc_json).unwrap();
+    //                 index_writer.add_document(doc).unwrap();
+    //             }
+    //         }
+    //     })
+    // });
+    // group.bench_function("index-hdfs-with-commit-with-docstore", |b| {
+    //     b.iter(|| {
+    //         let ram_directory = RamDirectory::create();
+    //         let mut index_writer = IndexBuilder::new()
+    //             .schema(schema.clone())
+    //             .single_segment_index_writer(ram_directory, 100_000_000)
+    //             .unwrap();
+    //         for _ in 0..NUM_REPEATS {
+    //             for doc_json in HDFS_LOGS.trim().split("\n") {
+    //                 let doc = schema.parse_document(doc_json).unwrap();
+    //                 index_writer.add_document(doc).unwrap();
+    //             }
+    //         }
+    //         index_writer.commit().unwrap();
+    //     })
+    // });
+    // group.bench_function("index-hdfs-no-commit-json-without-docstore", |b| {
+    //     b.iter(|| {
+    //         let ram_directory = RamDirectory::create();
+    //         let mut index_writer = IndexBuilder::new()
+    //             .schema(schema.clone())
+    //             .single_segment_index_writer(ram_directory, 100_000_000)
+    //             .unwrap();
+    //         for _ in 0..NUM_REPEATS {
+    //             for doc_json in HDFS_LOGS.trim().split("\n") {
+    //                 let json_val: serde_json::Map<String, serde_json::Value> =
+    //                     serde_json::from_str(doc_json).unwrap();
+    //                 let doc = tantivy::doc!(json_field=>json_val);
+    //                 index_writer.add_document(doc).unwrap();
+    //             }
+    //         }
+    //         index_writer.commit().unwrap();
+    //     })
+    // });
+    // group.bench_function("index-hdfs-with-commit-json-without-docstore", |b| {
+    //     b.iter(|| {
+    //         let ram_directory = RamDirectory::create();
+    //         let mut index_writer = IndexBuilder::new()
+    //             .schema(schema.clone())
+    //             .single_segment_index_writer(ram_directory, 100_000_000)
+    //             .unwrap();
+    //         for _ in 0..NUM_REPEATS {
+    //             for doc_json in HDFS_LOGS.trim().split("\n") {
+    //                 let json_val: serde_json::Map<String, serde_json::Value> =
+    //                     serde_json::from_str(doc_json).unwrap();
+    //                 let doc = tantivy::doc!(json_field=>json_val);
+    //                 index_writer.add_document(doc).unwrap();
+    //             }
+    //         }
+    //         index_writer.commit().unwrap();
+    //     })
+    //});
 }
 
 criterion_group! {

common/src/serialize.rs

@@ -1,3 +1,4 @@
+use std::borrow::Cow;
 use std::io::{Read, Write};
 use std::{fmt, io};
 
@@ -210,6 +211,23 @@ impl BinarySerializable for String {
     }
 }
 
+impl<'a> BinarySerializable for Cow<'a, str> {
+    fn serialize<W: Write>(&self, writer: &mut W) -> io::Result<()> {
+        let data: &[u8] = self.as_bytes();
+        VInt(data.len() as u64).serialize(writer)?;
+        writer.write_all(data)
+    }
+
+    fn deserialize<R: Read>(reader: &mut R) -> io::Result<Self> {
+        let string_length = VInt::deserialize(reader)?.val() as usize;
+        let mut result = String::with_capacity(string_length);
+        reader
+            .take(string_length as u64)
+            .read_to_string(&mut result)?;
+        Ok(Cow::Owned(result))
+    }
+}
+
 #[cfg(test)]
 pub mod test {
 

src/indexer/segment_writer.rs

@@ -158,7 +158,6 @@ impl SegmentWriter {
         let doc_id = self.max_doc;
         let vals_grouped_by_field = doc
             .field_values()
-            .iter()
             .sorted_by_key(|el| el.field())
             .group_by(|el| el.field());
         for (field, field_values) in &vals_grouped_by_field {
@@ -502,9 +501,17 @@ mod tests {
         let reader = StoreReader::open(directory.open_read(path).unwrap(), 0).unwrap();
         let doc = reader.get(0).unwrap();
 
-        assert_eq!(doc.field_values().len(), 2);
-        assert_eq!(doc.field_values()[0].value().as_text(), Some("A"));
-        assert_eq!(doc.field_values()[1].value().as_text(), Some("title"));
+        assert_eq!(doc.value_count(), 2);
+        let mut field_value_iter = doc.field_values();
+        assert_eq!(
+            field_value_iter.next().unwrap().value().as_text(),
+            Some("A")
+        );
+        assert_eq!(
+            field_value_iter.next().unwrap().value().as_text(),
+            Some("title")
+        );
+        assert!(field_value_iter.next().is_none());
     }
 
     #[test]
@@ -833,20 +840,23 @@ mod tests {
         // This is a bit of a contrived example.
         let tokens = PreTokenizedString {
             text: "contrived-example".to_string(), //< I can't think of a use case where this corner case happens in real life.
-            tokens: vec![Token { // Not the last token, yet ends after the last token.
-                offset_from: 0,
-                offset_to: 14,
-                position: 0,
-                text: "long_token".to_string(),
-                position_length: 3,
-            },
-            Token {
-                offset_from: 0,
-                offset_to: 14,
-                position: 1,
-                text: "short".to_string(),
-                position_length: 1,
-            }],
+            tokens: vec![
+                Token {
+                    // Not the last token, yet ends after the last token.
+                    offset_from: 0,
+                    offset_to: 14,
+                    position: 0,
+                    text: "long_token".to_string(),
+                    position_length: 3,
+                },
+                Token {
+                    offset_from: 0,
+                    offset_to: 14,
+                    position: 1,
+                    text: "short".to_string(),
+                    position_length: 1,
+                },
+            ],
         };
         doc.add_pre_tokenized_text(text, tokens);
         doc.add_text(text, "hello");

src/query/more_like_this/query.rs

@@ -31,7 +31,7 @@ pub struct MoreLikeThisQuery {
 #[derive(Debug, PartialEq, Clone)]
 enum TargetDocument {
     DocumentAdress(DocAddress),
-    DocumentFields(Vec<(Field, Vec<Value>)>),
+    DocumentFields(Vec<(Field, Vec<Value<'static>>)>),
 }
 
 impl MoreLikeThisQuery {
@@ -160,7 +160,10 @@ impl MoreLikeThisQueryBuilder {
     /// that will be used to compose the resulting query.
     /// This interface is meant to be used when you want to provide your own set of fields
     /// not necessarily from a specific document.
-    pub fn with_document_fields(self, doc_fields: Vec<(Field, Vec<Value>)>) -> MoreLikeThisQuery {
+    pub fn with_document_fields(
+        self,
+        doc_fields: Vec<(Field, Vec<Value<'static>>)>,
+    ) -> MoreLikeThisQuery {
         MoreLikeThisQuery {
             mlt: self.mlt,
             target: TargetDocument::DocumentFields(doc_fields),

src/schema/document.rs

@@ -1,35 +1,105 @@
 use std::collections::{HashMap, HashSet};
 use std::io::{self, Read, Write};
-use std::mem;
 use std::net::Ipv6Addr;
+use std::sync::Arc;
+use std::{fmt, mem};
 
 use common::{BinarySerializable, VInt};
+use itertools::Either;
+use yoke::erased::ErasedArcCart;
+use yoke::Yoke;
 
 use super::*;
+use crate::schema::value::MaybeOwnedString;
 use crate::tokenizer::PreTokenizedString;
 use crate::DateTime;
 
+/// A group of FieldValue sharing an underlying storage
+///
+/// Or a single owned FieldValue.
+#[derive(Clone)]
+enum FieldValueGroup {
+    Single(FieldValue<'static>),
+    Group(Yoke<VecFieldValue<'static>, ErasedArcCart>),
+}
+
+// this NewType is required to make it possible to yoke a vec with non 'static inner values.
+#[derive(yoke::Yokeable, Clone)]
+struct VecFieldValue<'a>(Vec<FieldValue<'a>>);
+
+impl<'a> std::ops::Deref for VecFieldValue<'a> {
+    type Target = Vec<FieldValue<'a>>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a> From<Vec<FieldValue<'a>>> for VecFieldValue<'a> {
+    fn from(field_values: Vec<FieldValue>) -> VecFieldValue {
+        VecFieldValue(field_values)
+    }
+}
+
+impl FieldValueGroup {
+    fn iter(&self) -> impl Iterator<Item = &FieldValue> {
+        match self {
+            FieldValueGroup::Single(field_value) => Either::Left(std::iter::once(field_value)),
+            FieldValueGroup::Group(field_values) => Either::Right(field_values.get().iter()),
+        }
+    }
+
+    fn count(&self) -> usize {
+        match self {
+            FieldValueGroup::Single(_) => 1,
+            FieldValueGroup::Group(field_values) => field_values.get().len(),
+        }
+    }
+}
+
+impl From<Vec<FieldValue<'static>>> for FieldValueGroup {
+    fn from(field_values: Vec<FieldValue<'static>>) -> FieldValueGroup {
+        FieldValueGroup::Group(
+            Yoke::new_always_owned(field_values.into())
+                .wrap_cart_in_arc()
+                .erase_arc_cart(),
+        )
+    }
+}
+
 /// Tantivy's Document is the object that can
 /// be indexed and then searched for.
 ///
 /// Documents are fundamentally a collection of unordered couples `(field, value)`.
 /// In this list, one field may appear more than once.
-#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, Default)]
+#[derive(Clone, Default)]
+// TODO bring back Ser/De and Debug
+//#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, Default)]
+//#[serde(bound(deserialize = "'static: 'de, 'de: 'static"))]
 pub struct Document {
-    field_values: Vec<FieldValue>,
+    field_values: Vec<FieldValueGroup>,
 }
 
-impl From<Vec<FieldValue>> for Document {
-    fn from(field_values: Vec<FieldValue>) -> Self {
+impl fmt::Debug for Document {
+    fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result {
+        todo!()
+    }
+}
+
+impl From<Vec<FieldValue<'static>>> for Document {
+    fn from(field_values: Vec<FieldValue<'static>>) -> Self {
+        let field_values = vec![field_values.into()];
         Document { field_values }
     }
 }
 impl PartialEq for Document {
     fn eq(&self, other: &Document) -> bool {
         // super slow, but only here for tests
-        let convert_to_comparable_map = |field_values: &[FieldValue]| {
+        let convert_to_comparable_map = |field_values| {
             let mut field_value_set: HashMap<Field, HashSet<String>> = Default::default();
-            for field_value in field_values.iter() {
+            for field_value in field_values {
+                // for some reason rustc fails to guess the type
+                let field_value: &FieldValue = field_value;
                 let json_val = serde_json::to_string(field_value.value()).unwrap();
                 field_value_set
                     .entry(field_value.field())
@@ -39,9 +109,9 @@ impl PartialEq for Document {
             field_value_set
         };
         let self_field_values: HashMap<Field, HashSet<String>> =
-            convert_to_comparable_map(&self.field_values);
+            convert_to_comparable_map(self.field_values());
         let other_field_values: HashMap<Field, HashSet<String>> =
-            convert_to_comparable_map(&other.field_values);
+            convert_to_comparable_map(other.field_values());
         self_field_values.eq(&other_field_values)
     }
 }
@@ -49,12 +119,13 @@ impl PartialEq for Document {
 impl Eq for Document {}
 
 impl IntoIterator for Document {
-    type Item = FieldValue;
+    type Item = FieldValue<'static>;
 
-    type IntoIter = std::vec::IntoIter<FieldValue>;
+    type IntoIter = std::vec::IntoIter<FieldValue<'static>>;
 
     fn into_iter(self) -> Self::IntoIter {
-        self.field_values.into_iter()
+        todo!()
+        // self.field_values.into_iter()
     }
 }
 
@@ -84,7 +155,7 @@ impl Document {
 
     /// Add a text field.
     pub fn add_text<S: ToString>(&mut self, field: Field, text: S) {
-        let value = Value::Str(text.to_string());
+        let value = Value::Str(MaybeOwnedString::from_string(text.to_string()));
         self.add_field_value(field, value);
     }
 
@@ -138,15 +209,35 @@ impl Document {
     }
 
     /// Add a (field, value) to the document.
-    pub fn add_field_value<T: Into<Value>>(&mut self, field: Field, typed_val: T) {
+    pub fn add_field_value<T: Into<Value<'static>>>(&mut self, field: Field, typed_val: T) {
         let value = typed_val.into();
         let field_value = FieldValue { field, value };
-        self.field_values.push(field_value);
+        self.field_values.push(FieldValueGroup::Single(field_value));
+    }
+
+    /// Add multiple borrowed values, also taking the container they're borrowing from
+    // TODO add a try_ variant?
+    pub fn add_borrowed_values<T, F>(&mut self, storage: T, f: F)
+    where
+        T: Send + Sync + 'static,
+        F: FnOnce(&T) -> Vec<FieldValue>,
+    {
+        let yoke =
+            Yoke::attach_to_cart(Arc::new(storage), |storage| f(storage).into()).erase_arc_cart();
+
+        self.field_values.push(FieldValueGroup::Group(yoke));
     }
 
     /// field_values accessor
-    pub fn field_values(&self) -> &[FieldValue] {
-        &self.field_values
+    pub fn field_values(&self) -> impl Iterator<Item = &FieldValue> {
+        self.field_values.iter().flat_map(|group| group.iter())
+    }
+
+    /// Return the total number of values
+    ///
+    /// More efficient than calling `self.field_values().count()`
+    pub fn value_count(&self) -> usize {
+        self.field_values.iter().map(|group| group.count()).sum()
     }
 
     /// Sort and groups the field_values by field.
@@ -154,7 +245,7 @@ impl Document {
     /// The result of this method is not cached and is
     /// computed on the fly when this method is called.
     pub fn get_sorted_field_values(&self) -> Vec<(Field, Vec<&Value>)> {
-        let mut field_values: Vec<&FieldValue> = self.field_values().iter().collect();
+        let mut field_values: Vec<&FieldValue> = self.field_values().collect();
         field_values.sort_by_key(|field_value| field_value.field());
 
         let mut field_values_it = field_values.into_iter();
@@ -189,6 +280,7 @@ impl Document {
     pub fn get_all(&self, field: Field) -> impl Iterator<Item = &Value> {
         self.field_values
             .iter()
+            .flat_map(|group| group.iter())
             .filter(move |field_value| field_value.field() == field)
             .map(FieldValue::value)
     }
@@ -202,7 +294,6 @@ impl Document {
     pub fn serialize_stored<W: Write>(&self, schema: &Schema, writer: &mut W) -> io::Result<()> {
         let stored_field_values = || {
             self.field_values()
-                .iter()
                 .filter(|field_value| schema.get_field_entry(field_value.field()).is_stored())
         };
         let num_field_values = stored_field_values().count();
@@ -216,7 +307,9 @@ impl Document {
                 } => {
                     let field_value = FieldValue {
                         field: *field,
-                        value: Value::Str(pre_tokenized_text.text.to_string()),
+                        value: Value::Str(MaybeOwnedString::from_string(
+                            pre_tokenized_text.text.to_string(),
+                        )),
                     };
                     field_value.serialize(writer)?;
                 }
@@ -230,7 +323,7 @@ impl Document {
 impl BinarySerializable for Document {
     fn serialize<W: Write>(&self, writer: &mut W) -> io::Result<()> {
         let field_values = self.field_values();
-        VInt(field_values.len() as u64).serialize(writer)?;
+        VInt(self.value_count() as u64).serialize(writer)?;
         for field_value in field_values {
             field_value.serialize(writer)?;
         }
@@ -259,7 +352,7 @@ mod tests {
         let text_field = schema_builder.add_text_field("title", TEXT);
         let mut doc = Document::default();
         doc.add_text(text_field, "My title");
-        assert_eq!(doc.field_values().len(), 1);
+        assert_eq!(doc.value_count(), 1);
     }
 
     #[test]
@@ -273,7 +366,7 @@ mod tests {
                 .clone(),
         );
         doc.add_text(Field::from_field_id(1), "hello");
-        assert_eq!(doc.field_values().len(), 2);
+        assert_eq!(doc.value_count(), 2);
         let mut payload: Vec<u8> = Vec::new();
         doc.serialize(&mut payload).unwrap();
         assert_eq!(payload.len(), 26);

src/schema/field_type.rs

@@ -9,6 +9,7 @@ use super::ip_options::IpAddrOptions;
 use super::{Cardinality, IntoIpv6Addr};
 use crate::schema::bytes_options::BytesOptions;
 use crate::schema::facet_options::FacetOptions;
+use crate::schema::value::MaybeOwnedString;
 use crate::schema::{
     DateOptions, Facet, IndexRecordOption, JsonObjectOptions, NumericOptions, TextFieldIndexing,
     TextOptions, Value,
@@ -329,7 +330,7 @@ impl FieldType {
     /// Tantivy will not try to cast values.
     /// For instance, If the json value is the integer `3` and the
     /// target field is a `Str`, this method will return an Error.
-    pub fn value_from_json(&self, json: JsonValue) -> Result<Value, ValueParsingError> {
+    pub fn value_from_json(&self, json: JsonValue) -> Result<Value<'static>, ValueParsingError> {
         match json {
             JsonValue::String(field_text) => {
                 match self {
@@ -341,7 +342,7 @@ impl FieldType {
                             })?;
                         Ok(DateTime::from_utc(dt_with_fixed_tz).into())
                     }
-                    FieldType::Str(_) => Ok(Value::Str(field_text)),
+                    FieldType::Str(_) => Ok(Value::Str(MaybeOwnedString::from_string(field_text))),
                     FieldType::U64(_) | FieldType::I64(_) | FieldType::F64(_) => {
                         Err(ValueParsingError::TypeError {
                             expected: "an integer",

src/schema/field_value.rs

@@ -7,12 +7,13 @@ use crate::schema::{Field, Value};
 /// `FieldValue` holds together a `Field` and its `Value`.
 #[allow(missing_docs)]
 #[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
-pub struct FieldValue {
+#[serde(bound(deserialize = "'a: 'de, 'de: 'a"))]
+pub struct FieldValue<'a> {
     pub field: Field,
-    pub value: Value,
+    pub value: Value<'a>,
 }
 
-impl FieldValue {
+impl<'a> FieldValue<'a> {
     /// Constructor
     pub fn new(field: Field, value: Value) -> FieldValue {
         FieldValue { field, value }
@@ -29,13 +30,13 @@ impl FieldValue {
     }
 }
 
-impl From<FieldValue> for Value {
-    fn from(field_value: FieldValue) -> Self {
+impl<'a> From<FieldValue<'a>> for Value<'a> {
+    fn from(field_value: FieldValue<'a>) -> Self {
         field_value.value
     }
 }
 
-impl BinarySerializable for FieldValue {
+impl<'a> BinarySerializable for FieldValue<'a> {
     fn serialize<W: Write>(&self, writer: &mut W) -> io::Result<()> {
         self.field.serialize(writer)?;
         self.value.serialize(writer)

src/schema/named_field_document.rs

@@ -10,4 +10,5 @@ use crate::schema::Value;
 /// A `NamedFieldDocument` is a simple representation of a document
 /// as a `BTreeMap<String, Vec<Value>>`.
 #[derive(Debug, Deserialize, Serialize)]
-pub struct NamedFieldDocument(pub BTreeMap<String, Vec<Value>>);
+#[serde(bound(deserialize = "'static: 'de, 'de: 'static"))]
+pub struct NamedFieldDocument(pub BTreeMap<String, Vec<Value<'static>>>);

src/schema/schema.rs

@@ -308,7 +308,11 @@ impl Schema {
         let mut field_map = BTreeMap::new();
         for (field, field_values) in doc.get_sorted_field_values() {
             let field_name = self.get_field_name(field);
-            let values: Vec<Value> = field_values.into_iter().cloned().collect();
+            let values: Vec<Value> = field_values
+                .into_iter()
+                .cloned()
+                .map(Value::into_owned)
+                .collect();
             field_map.insert(field_name.to_string(), values);
         }
         NamedFieldDocument(field_map)
@@ -338,20 +342,21 @@ impl Schema {
             if let Some(field) = self.get_field(&field_name) {
                 let field_entry = self.get_field_entry(field);
                 let field_type = field_entry.field_type();
+                // TODO rewrite this with shared allocation?
                 match json_value {
                     JsonValue::Array(json_items) => {
                         for json_item in json_items {
                             let value = field_type
                                 .value_from_json(json_item)
                                 .map_err(|e| DocParsingError::ValueError(field_name.clone(), e))?;
-                            doc.add_field_value(field, value);
+                            doc.add_field_value(field, value.into_owned());
                         }
                     }
                     _ => {
                         let value = field_type
                             .value_from_json(json_value)
                             .map_err(|e| DocParsingError::ValueError(field_name.clone(), e))?;
-                        doc.add_field_value(field, value);
+                        doc.add_field_value(field, value.into_owned());
                     }
                 }
             }
@@ -706,7 +711,7 @@ mod tests {
         let schema = schema_builder.build();
         {
             let doc = schema.parse_document("{}").unwrap();
-            assert!(doc.field_values().is_empty());
+            assert_eq!(doc.value_count(), 0);
         }
         {
             let doc = schema

src/schema/value.rs

@@ -1,6 +1,7 @@
 use std::fmt;
 use std::net::Ipv6Addr;
 
+pub use not_safe::MaybeOwnedString;
 use serde::de::Visitor;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 use serde_json::Map;
@@ -12,9 +13,9 @@ use crate::DateTime;
 /// Value represents the value of a any field.
 /// It is an enum over all over all of the possible field type.
 #[derive(Debug, Clone, PartialEq)]
-pub enum Value {
+pub enum Value<'a> {
     /// The str type is used for any text information.
-    Str(String),
+    Str(MaybeOwnedString<'a>),
     /// Pre-tokenized str type,
     PreTokStr(PreTokenizedString),
     /// Unsigned 64-bits Integer `u64`
@@ -30,16 +31,38 @@ pub enum Value {
     /// Facet
     Facet(Facet),
     /// Arbitrarily sized byte array
+    // TODO allow Cow<'a, [u8]>
     Bytes(Vec<u8>),
     /// Json object value.
+    // TODO allow Cow keys and borrowed values
     JsonObject(serde_json::Map<String, serde_json::Value>),
     /// IpV6 Address. Internally there is no IpV4, it needs to be converted to `Ipv6Addr`.
     IpAddr(Ipv6Addr),
 }
 
-impl Eq for Value {}
+impl<'a> Value<'a> {
+    /// Convert a borrowing [`Value`] to an owning one.
+    pub fn into_owned(self) -> Value<'static> {
+        use Value::*;
+        match self {
+            Str(val) => Str(MaybeOwnedString::from_string(val.into_string())),
+            PreTokStr(val) => PreTokStr(val),
+            U64(val) => U64(val),
+            I64(val) => I64(val),
+            F64(val) => F64(val),
+            Bool(val) => Bool(val),
+            Date(val) => Date(val),
+            Facet(val) => Facet(val),
+            Bytes(val) => Bytes(val),
+            JsonObject(val) => JsonObject(val),
+            IpAddr(val) => IpAddr(val),
+        }
+    }
+}
 
-impl Serialize for Value {
+impl<'a> Eq for Value<'a> {}
+
+impl<'a> Serialize for Value<'a> {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where S: Serializer {
         match *self {
@@ -65,13 +88,13 @@ impl Serialize for Value {
     }
 }
 
-impl<'de> Deserialize<'de> for Value {
+impl<'de> Deserialize<'de> for Value<'de> {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where D: Deserializer<'de> {
         struct ValueVisitor;
 
         impl<'de> Visitor<'de> for ValueVisitor {
-            type Value = Value;
+            type Value = Value<'de>;
 
             fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("a string or u32")
@@ -93,12 +116,13 @@ impl<'de> Deserialize<'de> for Value {
                 Ok(Value::Bool(v))
             }
 
+            // TODO add visit_borrowed_str
             fn visit_str<E>(self, v: &str) -> Result<Self::Value, E> {
-                Ok(Value::Str(v.to_owned()))
+                Ok(Value::Str(MaybeOwnedString::from_string(v.to_owned())))
             }
 
             fn visit_string<E>(self, v: String) -> Result<Self::Value, E> {
-                Ok(Value::Str(v))
+                Ok(Value::Str(MaybeOwnedString::from_string(v)))
             }
         }
 
@@ -106,7 +130,7 @@ impl<'de> Deserialize<'de> for Value {
     }
 }
 
-impl Value {
+impl<'a> Value<'a> {
     /// Returns the text value, provided the value is of the `Str` type.
     /// (Returns `None` if the value is not of the `Str` type).
     pub fn as_text(&self) -> Option<&str> {
@@ -224,86 +248,87 @@ impl Value {
     }
 }
 
-impl From<String> for Value {
-    fn from(s: String) -> Value {
-        Value::Str(s)
+impl From<String> for Value<'static> {
+    fn from(s: String) -> Value<'static> {
+        Value::Str(MaybeOwnedString::from_string(s))
     }
 }
 
-impl From<Ipv6Addr> for Value {
-    fn from(v: Ipv6Addr) -> Value {
+impl From<Ipv6Addr> for Value<'static> {
+    fn from(v: Ipv6Addr) -> Value<'static> {
         Value::IpAddr(v)
     }
 }
 
-impl From<u64> for Value {
-    fn from(v: u64) -> Value {
+impl From<u64> for Value<'static> {
+    fn from(v: u64) -> Value<'static> {
         Value::U64(v)
     }
 }
 
-impl From<i64> for Value {
-    fn from(v: i64) -> Value {
+impl From<i64> for Value<'static> {
+    fn from(v: i64) -> Value<'static> {
         Value::I64(v)
     }
 }
 
-impl From<f64> for Value {
-    fn from(v: f64) -> Value {
+impl From<f64> for Value<'static> {
+    fn from(v: f64) -> Value<'static> {
         Value::F64(v)
     }
 }
 
-impl From<bool> for Value {
+impl From<bool> for Value<'static> {
     fn from(b: bool) -> Self {
         Value::Bool(b)
     }
 }
 
-impl From<DateTime> for Value {
-    fn from(dt: DateTime) -> Value {
+impl From<DateTime> for Value<'static> {
+    fn from(dt: DateTime) -> Value<'static> {
         Value::Date(dt)
     }
 }
 
-impl<'a> From<&'a str> for Value {
-    fn from(s: &'a str) -> Value {
-        Value::Str(s.to_string())
+impl<'a> From<&'a str> for Value<'a> {
+    fn from(s: &'a str) -> Value<'a> {
+        Value::Str(MaybeOwnedString::from_str(s))
     }
 }
 
-impl<'a> From<&'a [u8]> for Value {
-    fn from(bytes: &'a [u8]) -> Value {
+// TODO change lifetime to 'a
+impl<'a> From<&'a [u8]> for Value<'static> {
+    fn from(bytes: &'a [u8]) -> Value<'static> {
         Value::Bytes(bytes.to_vec())
     }
 }
 
-impl From<Facet> for Value {
-    fn from(facet: Facet) -> Value {
+impl From<Facet> for Value<'static> {
+    fn from(facet: Facet) -> Value<'static> {
         Value::Facet(facet)
     }
 }
 
-impl From<Vec<u8>> for Value {
-    fn from(bytes: Vec<u8>) -> Value {
+impl From<Vec<u8>> for Value<'static> {
+    fn from(bytes: Vec<u8>) -> Value<'static> {
         Value::Bytes(bytes)
     }
 }
 
-impl From<PreTokenizedString> for Value {
-    fn from(pretokenized_string: PreTokenizedString) -> Value {
+impl From<PreTokenizedString> for Value<'static> {
+    fn from(pretokenized_string: PreTokenizedString) -> Value<'static> {
         Value::PreTokStr(pretokenized_string)
     }
 }
 
-impl From<serde_json::Map<String, serde_json::Value>> for Value {
-    fn from(json_object: serde_json::Map<String, serde_json::Value>) -> Value {
+impl From<serde_json::Map<String, serde_json::Value>> for Value<'static> {
+    fn from(json_object: serde_json::Map<String, serde_json::Value>) -> Value<'static> {
         Value::JsonObject(json_object)
     }
 }
 
-impl From<serde_json::Value> for Value {
-    fn from(json_value: serde_json::Value) -> Value {
+impl From<serde_json::Value> for Value<'static> {
+    fn from(json_value: serde_json::Value) -> Value<'static> {
         match json_value {
             serde_json::Value::Object(json_object) => Value::JsonObject(json_object),
             _ => {
@@ -320,7 +345,7 @@ mod binary_serialize {
     use common::{f64_to_u64, u64_to_f64, BinarySerializable};
     use fastfield_codecs::MonotonicallyMappableToU128;
 
-    use super::Value;
+    use super::{MaybeOwnedString, Value};
     use crate::schema::Facet;
     use crate::tokenizer::PreTokenizedString;
     use crate::DateTime;
@@ -341,12 +366,13 @@ mod binary_serialize {
 
     const TOK_STR_CODE: u8 = 0;
 
-    impl BinarySerializable for Value {
+    impl<'a> BinarySerializable for Value<'a> {
         fn serialize<W: Write>(&self, writer: &mut W) -> io::Result<()> {
             match *self {
                 Value::Str(ref text) => {
                     TEXT_CODE.serialize(writer)?;
-                    text.serialize(writer)
+                    // TODO impl trait for MaybeOwnedString
+                    text.as_str().to_owned().serialize(writer)
                 }
                 Value::PreTokStr(ref tok_str) => {
                     EXT_CODE.serialize(writer)?;
@@ -408,7 +434,7 @@ mod binary_serialize {
             match type_code {
                 TEXT_CODE => {
                     let text = String::deserialize(reader)?;
-                    Ok(Value::Str(text))
+                    Ok(Value::Str(MaybeOwnedString::from_string(text)))
                 }
                 U64_CODE => {
                     let value = u64::deserialize(reader)?;
@@ -550,3 +576,104 @@ mod tests {
         assert_eq!(serialized_value_json, r#""1996-12-20T01:39:57Z""#);
     }
 }
+
+mod not_safe {
+    use std::ops::Deref;
+
+    union Ref<'a, T: ?Sized> {
+        shared: &'a T,
+        uniq: &'a mut T,
+    }
+
+    pub struct MaybeOwnedString<'a> {
+        string: Ref<'a, str>,
+        capacity: usize,
+    }
+
+    impl<'a> MaybeOwnedString<'a> {
+        pub fn from_str(string: &'a str) -> MaybeOwnedString<'a> {
+            MaybeOwnedString {
+                string: Ref { shared: string },
+                capacity: 0,
+            }
+        }
+
+        pub fn from_string(mut string: String) -> MaybeOwnedString<'static> {
+            string.shrink_to_fit(); // <= actually important for safety, todo use the Vec .as_ptr instead
+
+            let mut s = std::mem::ManuallyDrop::new(string);
+            let ptr = s.as_mut_ptr();
+            let len = s.len();
+            let capacity = s.capacity();
+
+            let string = unsafe {
+                std::str::from_utf8_unchecked_mut(std::slice::from_raw_parts_mut(ptr, len))
+            };
+            MaybeOwnedString {
+                string: Ref { uniq: string },
+                capacity,
+            }
+        }
+
+        pub fn into_string(mut self) -> String {
+            if self.capacity != 0 {
+                let string = unsafe { &mut self.string.uniq };
+                unsafe {
+                    return String::from_raw_parts(string.as_mut_ptr(), self.len(), self.capacity);
+                };
+            }
+            self.deref().to_owned()
+        }
+
+        pub fn as_str(&self) -> &str {
+            self.deref()
+        }
+    }
+
+    impl<'a> Deref for MaybeOwnedString<'a> {
+        type Target = str;
+
+        #[inline]
+        fn deref(&self) -> &str {
+            unsafe { self.string.shared }
+        }
+    }
+
+    impl<'a> Drop for MaybeOwnedString<'a> {
+        fn drop(&mut self) {
+            // if capacity is 0, either it's an empty String so there is no dealloc to do, or it's
+            // borrowed
+            if self.capacity != 0 {
+                let string = unsafe { &mut self.string.uniq };
+                unsafe { String::from_raw_parts(string.as_mut_ptr(), self.len(), self.capacity) };
+            }
+        }
+    }
+
+    impl<'a> Clone for MaybeOwnedString<'a> {
+        fn clone(&self) -> Self {
+            if self.capacity == 0 {
+                MaybeOwnedString {
+                    string: Ref {
+                        shared: unsafe { self.string.shared },
+                    },
+                    capacity: 0,
+                }
+            } else {
+                MaybeOwnedString::from_string(self.deref().to_owned())
+            }
+        }
+    }
+
+    impl<'a> std::fmt::Debug for MaybeOwnedString<'a> {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            f.write_str(self.deref())
+        }
+    }
+
+    impl<'a> PartialEq for MaybeOwnedString<'a> {
+        fn eq(&self, other: &Self) -> bool {
+            self.deref() == other.deref()
+        }
+    }
+}