Merge pull request #244 from meilisearch/reintroduce-stop-words

Reintroduce stop words

meilidb-core/src/raw_indexer.rs

@@ -11,6 +11,7 @@ type Word = Vec<u8>; // TODO make it be a SmallVec
 
 pub struct RawIndexer {
     word_limit: usize, // the maximum number of indexed words
+    stop_words: fst::Set,
     words_doc_indexes: BTreeMap<Word, Vec<DocIndex>>,
     docs_words: HashMap<DocumentId, Vec<Word>>,
 }
@@ -21,13 +22,14 @@ pub struct Indexed {
 }
 
 impl RawIndexer {
-    pub fn new() -> RawIndexer {
+    pub fn new(stop_words: fst::Set) -> RawIndexer {
-        RawIndexer::with_word_limit(1000)
+        RawIndexer::with_word_limit(stop_words, 1000)
     }
 
-    pub fn with_word_limit(limit: usize) -> RawIndexer {
+    pub fn with_word_limit(stop_words: fst::Set, limit: usize) -> RawIndexer {
         RawIndexer {
             word_limit: limit,
+            stop_words,
             words_doc_indexes: BTreeMap::new(),
             docs_words: HashMap::new(),
         }
@@ -56,6 +58,7 @@ impl RawIndexer {
                     id,
                     attr,
                     self.word_limit,
+                    &self.stop_words,
                     &mut self.words_doc_indexes,
                     &mut self.docs_words,
                 );
@@ -87,6 +90,7 @@ impl RawIndexer {
                 id,
                 attr,
                 self.word_limit,
+                &self.stop_words,
                 &mut self.words_doc_indexes,
                 &mut self.docs_words,
             );
@@ -118,6 +122,7 @@ impl RawIndexer {
                 id,
                 attr,
                 self.word_limit,
+                &self.stop_words,
                 &mut self.words_doc_indexes,
                 &mut self.docs_words,
             );
@@ -152,17 +157,12 @@ impl RawIndexer {
     }
 }
 
-impl Default for RawIndexer {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
 fn index_token(
     token: Token,
     id: DocumentId,
     attr: SchemaAttr,
     word_limit: usize,
+    stop_words: &fst::Set,
     words_doc_indexes: &mut BTreeMap<Word, Vec<DocIndex>>,
     docs_words: &mut HashMap<DocumentId, Vec<Word>>,
 ) -> bool {
@@ -170,6 +170,7 @@ fn index_token(
         return false;
     }
 
+    if !stop_words.contains(&token.word) {
         match token_to_docindex(id, attr, token) {
             Some(docindex) => {
                 let word = Vec::from(token.word);
@@ -181,6 +182,7 @@ fn index_token(
             }
             None => return false,
         }
+    }
 
     true
 }
@@ -207,7 +209,7 @@ mod tests {
 
     #[test]
     fn strange_apostrophe() {
-        let mut indexer = RawIndexer::new();
+        let mut indexer = RawIndexer::new(fst::Set::default());
 
         let docid = DocumentId(0);
         let attr = SchemaAttr(0);
@@ -231,7 +233,7 @@ mod tests {
 
     #[test]
     fn strange_apostrophe_in_sequence() {
-        let mut indexer = RawIndexer::new();
+        let mut indexer = RawIndexer::new(fst::Set::default());
 
         let docid = DocumentId(0);
         let attr = SchemaAttr(0);
@@ -252,4 +254,33 @@ mod tests {
             .get(&"l’éteindre".to_owned().into_bytes())
             .is_some());
     }
+
+    #[test]
+    fn basic_stop_words() {
+        let stop_words = sdset::SetBuf::from_dirty(vec!["l", "j", "ai", "de"]);
+        let stop_words = fst::Set::from_iter(stop_words).unwrap();
+
+        let mut indexer = RawIndexer::new(stop_words);
+
+        let docid = DocumentId(0);
+        let attr = SchemaAttr(0);
+        let text = "Zut, l’aspirateur, j’ai oublié de l’éteindre !";
+        indexer.index_text(docid, attr, text);
+
+        let Indexed {
+            words_doc_indexes, ..
+        } = indexer.build();
+
+        assert!(words_doc_indexes.get(&b"l"[..]).is_none());
+        assert!(words_doc_indexes.get(&b"aspirateur"[..]).is_some());
+        assert!(words_doc_indexes.get(&b"j"[..]).is_none());
+        assert!(words_doc_indexes.get(&b"ai"[..]).is_none());
+        assert!(words_doc_indexes.get(&b"de"[..]).is_none());
+        assert!(words_doc_indexes.get(&b"eteindre"[..]).is_some());
+
+        // with the ugly apostrophe...
+        assert!(words_doc_indexes
+            .get(&"l’éteindre".to_owned().into_bytes())
+            .is_some());
+    }
 }

meilidb-core/src/store/main.rs

@@ -9,6 +9,7 @@ const NUMBER_OF_DOCUMENTS_KEY: &str = "number-of-documents";
 const RANKED_MAP_KEY: &str = "ranked-map";
 const SCHEMA_KEY: &str = "schema";
 const SYNONYMS_KEY: &str = "synonyms";
+const STOP_WORDS_KEY: &str = "stop-words";
 const WORDS_KEY: &str = "words";
 
 #[derive(Copy, Clone)]
@@ -71,6 +72,24 @@ impl Main {
         }
     }
 
+    pub fn put_stop_words_fst(self, writer: &mut heed::RwTxn, fst: &fst::Set) -> ZResult<()> {
+        let bytes = fst.as_fst().as_bytes();
+        self.main
+            .put::<Str, ByteSlice>(writer, STOP_WORDS_KEY, bytes)
+    }
+
+    pub fn stop_words_fst(self, reader: &heed::RoTxn) -> ZResult<Option<fst::Set>> {
+        match self.main.get::<Str, ByteSlice>(reader, STOP_WORDS_KEY)? {
+            Some(bytes) => {
+                let len = bytes.len();
+                let bytes = Arc::from(bytes);
+                let fst = fst::raw::Fst::from_shared_bytes(bytes, 0, len).unwrap();
+                Ok(Some(fst::Set::from(fst)))
+            }
+            None => Ok(None),
+        }
+    }
+
     pub fn put_number_of_documents<F>(self, writer: &mut heed::RwTxn, f: F) -> ZResult<u64>
     where
         F: Fn(u64) -> u64,

meilidb-core/src/store/mod.rs

@@ -187,6 +187,22 @@ impl Index {
         )
     }
 
+    pub fn stop_words_addition(&self) -> update::StopWordsAddition {
+        update::StopWordsAddition::new(
+            self.updates,
+            self.updates_results,
+            self.updates_notifier.clone(),
+        )
+    }
+
+    pub fn stop_words_deletion(&self) -> update::StopWordsDeletion {
+        update::StopWordsDeletion::new(
+            self.updates,
+            self.updates_results,
+            self.updates_notifier.clone(),
+        )
+    }
+
     pub fn current_update_id(&self, reader: &heed::RoTxn) -> MResult<Option<u64>> {
         match self.updates.last_update_id(reader)? {
             Some((id, _)) => Ok(Some(id)),

meilidb-core/src/update/documents_addition.rs

@@ -87,7 +87,6 @@ pub fn apply_documents_addition(
     addition: Vec<serde_json::Value>,
 ) -> MResult<()> {
     let mut documents_additions = HashMap::new();
-    let mut indexer = RawIndexer::new();
 
     let schema = match main_store.schema(writer)? {
         Some(schema) => schema,
@@ -124,7 +123,14 @@ pub fn apply_documents_addition(
         None => RankedMap::default(),
     };
 
+    let stop_words = match main_store.stop_words_fst(writer)? {
+        Some(stop_words) => stop_words,
+        None => fst::Set::default(),
+    };
+
     // 3. index the documents fields in the stores
+    let mut indexer = RawIndexer::new(stop_words);
+
     for (document_id, document) in documents_additions {
         let serializer = Serializer {
             txn: writer,
@@ -180,8 +186,13 @@ pub fn reindex_all_documents(
     postings_lists_store.clear(writer)?;
     docs_words_store.clear(writer)?;
 
+    let stop_words = match main_store.stop_words_fst(writer)? {
+        Some(stop_words) => stop_words,
+        None => fst::Set::default(),
+    };
+
     // 3. re-index one document by one document (otherwise we make the borrow checker unhappy)
-    let mut indexer = RawIndexer::new();
+    let mut indexer = RawIndexer::new(stop_words);
     let mut ram_store = HashMap::new();
 
     for document_id in documents_ids_to_reindex {

meilidb-core/src/update/mod.rs

@@ -3,6 +3,8 @@ mod customs_update;
 mod documents_addition;
 mod documents_deletion;
 mod schema_update;
+mod stop_words_addition;
+mod stop_words_deletion;
 mod synonyms_addition;
 mod synonyms_deletion;
 
@@ -11,11 +13,13 @@ pub use self::customs_update::{apply_customs_update, push_customs_update};
 pub use self::documents_addition::{apply_documents_addition, DocumentsAddition};
 pub use self::documents_deletion::{apply_documents_deletion, DocumentsDeletion};
 pub use self::schema_update::{apply_schema_update, push_schema_update};
+pub use self::stop_words_addition::{apply_stop_words_addition, StopWordsAddition};
+pub use self::stop_words_deletion::{apply_stop_words_deletion, StopWordsDeletion};
 pub use self::synonyms_addition::{apply_synonyms_addition, SynonymsAddition};
 pub use self::synonyms_deletion::{apply_synonyms_deletion, SynonymsDeletion};
 
 use std::cmp;
-use std::collections::BTreeMap;
+use std::collections::{BTreeMap, BTreeSet};
 use std::time::{Duration, Instant};
 
 use heed::Result as ZResult;
@@ -34,6 +38,8 @@ pub enum Update {
     DocumentsDeletion(Vec<DocumentId>),
     SynonymsAddition(BTreeMap<String, Vec<String>>),
     SynonymsDeletion(BTreeMap<String, Option<Vec<String>>>),
+    StopWordsAddition(BTreeSet<String>),
+    StopWordsDeletion(BTreeSet<String>),
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -45,6 +51,8 @@ pub enum UpdateType {
     DocumentsDeletion { number: usize },
     SynonymsAddition { number: usize },
     SynonymsDeletion { number: usize },
+    StopWordsAddition { number: usize },
+    StopWordsDeletion { number: usize },
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -210,6 +218,37 @@ pub fn update_task(writer: &mut heed::RwTxn, index: store::Index) -> MResult<Opt
 
             let result = apply_synonyms_deletion(writer, index.main, index.synonyms, synonyms);
 
+            (update_type, result, start.elapsed())
+        }
+        Update::StopWordsAddition(stop_words) => {
+            let start = Instant::now();
+
+            let update_type = UpdateType::StopWordsAddition {
+                number: stop_words.len(),
+            };
+
+            let result =
+                apply_stop_words_addition(writer, index.main, index.postings_lists, stop_words);
+
+            (update_type, result, start.elapsed())
+        }
+        Update::StopWordsDeletion(stop_words) => {
+            let start = Instant::now();
+
+            let update_type = UpdateType::StopWordsDeletion {
+                number: stop_words.len(),
+            };
+
+            let result = apply_stop_words_deletion(
+                writer,
+                index.main,
+                index.documents_fields,
+                index.documents_fields_counts,
+                index.postings_lists,
+                index.docs_words,
+                stop_words,
+            );
+
             (update_type, result, start.elapsed())
         }
     };

meilidb-core/src/update/stop_words_addition.rs

@@ -0,0 +1,116 @@
+use std::collections::BTreeSet;
+
+use fst::{set::OpBuilder, SetBuilder};
+
+use crate::automaton::normalize_str;
+use crate::update::{next_update_id, Update};
+use crate::{store, MResult};
+
+pub struct StopWordsAddition {
+    updates_store: store::Updates,
+    updates_results_store: store::UpdatesResults,
+    updates_notifier: crossbeam_channel::Sender<()>,
+    stop_words: BTreeSet<String>,
+}
+
+impl StopWordsAddition {
+    pub fn new(
+        updates_store: store::Updates,
+        updates_results_store: store::UpdatesResults,
+        updates_notifier: crossbeam_channel::Sender<()>,
+    ) -> StopWordsAddition {
+        StopWordsAddition {
+            updates_store,
+            updates_results_store,
+            updates_notifier,
+            stop_words: BTreeSet::new(),
+        }
+    }
+
+    pub fn add_stop_word<S: AsRef<str>>(&mut self, stop_word: S) {
+        let stop_word = normalize_str(stop_word.as_ref());
+        self.stop_words.insert(stop_word);
+    }
+
+    pub fn finalize(self, writer: &mut heed::RwTxn) -> MResult<u64> {
+        let _ = self.updates_notifier.send(());
+        let update_id = push_stop_words_addition(
+            writer,
+            self.updates_store,
+            self.updates_results_store,
+            self.stop_words,
+        )?;
+        Ok(update_id)
+    }
+}
+
+pub fn push_stop_words_addition(
+    writer: &mut heed::RwTxn,
+    updates_store: store::Updates,
+    updates_results_store: store::UpdatesResults,
+    addition: BTreeSet<String>,
+) -> MResult<u64> {
+    let last_update_id = next_update_id(writer, updates_store, updates_results_store)?;
+
+    let update = Update::StopWordsAddition(addition);
+    updates_store.put_update(writer, last_update_id, &update)?;
+
+    Ok(last_update_id)
+}
+
+pub fn apply_stop_words_addition(
+    writer: &mut heed::RwTxn,
+    main_store: store::Main,
+    postings_lists_store: store::PostingsLists,
+    addition: BTreeSet<String>,
+) -> MResult<()> {
+    let mut stop_words_builder = SetBuilder::memory();
+
+    for word in addition {
+        stop_words_builder.insert(&word).unwrap();
+        // we remove every posting list associated to a new stop word
+        postings_lists_store.del_postings_list(writer, word.as_bytes())?;
+    }
+
+    // create the new delta stop words fst
+    let delta_stop_words = stop_words_builder
+        .into_inner()
+        .and_then(fst::Set::from_bytes)
+        .unwrap();
+
+    // we also need to remove all the stop words from the main fst
+    if let Some(word_fst) = main_store.words_fst(writer)? {
+        let op = OpBuilder::new()
+            .add(&word_fst)
+            .add(&delta_stop_words)
+            .difference();
+
+        let mut word_fst_builder = SetBuilder::memory();
+        word_fst_builder.extend_stream(op).unwrap();
+        let word_fst = word_fst_builder
+            .into_inner()
+            .and_then(fst::Set::from_bytes)
+            .unwrap();
+
+        main_store.put_words_fst(writer, &word_fst)?;
+    }
+
+    // now we add all of these stop words from the main store
+    let stop_words_fst = main_store.stop_words_fst(writer)?.unwrap_or_default();
+
+    let op = OpBuilder::new()
+        .add(&stop_words_fst)
+        .add(&delta_stop_words)
+        .r#union();
+
+    let mut stop_words_builder = SetBuilder::memory();
+    stop_words_builder.extend_stream(op).unwrap();
+    let stop_words_fst = stop_words_builder
+        .into_inner()
+        .and_then(fst::Set::from_bytes)
+        .unwrap();
+
+    main_store.put_stop_words_fst(writer, &stop_words_fst)?;
+
+    Ok(())
+}

meilidb-core/src/update/stop_words_deletion.rs

@@ -0,0 +1,112 @@
+use std::collections::BTreeSet;
+
+use fst::{set::OpBuilder, SetBuilder};
+
+use crate::automaton::normalize_str;
+use crate::update::documents_addition::reindex_all_documents;
+use crate::update::{next_update_id, Update};
+use crate::{store, MResult};
+
+pub struct StopWordsDeletion {
+    updates_store: store::Updates,
+    updates_results_store: store::UpdatesResults,
+    updates_notifier: crossbeam_channel::Sender<()>,
+    stop_words: BTreeSet<String>,
+}
+
+impl StopWordsDeletion {
+    pub fn new(
+        updates_store: store::Updates,
+        updates_results_store: store::UpdatesResults,
+        updates_notifier: crossbeam_channel::Sender<()>,
+    ) -> StopWordsDeletion {
+        StopWordsDeletion {
+            updates_store,
+            updates_results_store,
+            updates_notifier,
+            stop_words: BTreeSet::new(),
+        }
+    }
+
+    pub fn delete_stop_word<S: AsRef<str>>(&mut self, stop_word: S) {
+        let stop_word = normalize_str(stop_word.as_ref());
+        self.stop_words.insert(stop_word);
+    }
+
+    pub fn finalize(self, writer: &mut heed::RwTxn) -> MResult<u64> {
+        let _ = self.updates_notifier.send(());
+        let update_id = push_stop_words_deletion(
+            writer,
+            self.updates_store,
+            self.updates_results_store,
+            self.stop_words,
+        )?;
+        Ok(update_id)
+    }
+}
+
+pub fn push_stop_words_deletion(
+    writer: &mut heed::RwTxn,
+    updates_store: store::Updates,
+    updates_results_store: store::UpdatesResults,
+    deletion: BTreeSet<String>,
+) -> MResult<u64> {
+    let last_update_id = next_update_id(writer, updates_store, updates_results_store)?;
+
+    let update = Update::StopWordsDeletion(deletion);
+    updates_store.put_update(writer, last_update_id, &update)?;
+
+    Ok(last_update_id)
+}
+
+pub fn apply_stop_words_deletion(
+    writer: &mut heed::RwTxn,
+    main_store: store::Main,
+    documents_fields_store: store::DocumentsFields,
+    documents_fields_counts_store: store::DocumentsFieldsCounts,
+    postings_lists_store: store::PostingsLists,
+    docs_words_store: store::DocsWords,
+    deletion: BTreeSet<String>,
+) -> MResult<()> {
+    let mut stop_words_builder = SetBuilder::memory();
+
+    for word in deletion {
+        stop_words_builder.insert(&word).unwrap();
+    }
+
+    // create the new delta stop words fst
+    let delta_stop_words = stop_words_builder
+        .into_inner()
+        .and_then(fst::Set::from_bytes)
+        .unwrap();
+
+    // now we delete all of these stop words from the main store
+    let stop_words_fst = main_store.stop_words_fst(writer)?.unwrap_or_default();
+
+    let op = OpBuilder::new()
+        .add(&stop_words_fst)
+        .add(&delta_stop_words)
+        .difference();
+
+    let mut stop_words_builder = SetBuilder::memory();
+    stop_words_builder.extend_stream(op).unwrap();
+    let stop_words_fst = stop_words_builder
+        .into_inner()
+        .and_then(fst::Set::from_bytes)
+        .unwrap();
+
+    main_store.put_stop_words_fst(writer, &stop_words_fst)?;
+
+    // now that we have setup the stop words
+    // lets reindex everything...
+    reindex_all_documents(
+        writer,
+        main_store,
+        documents_fields_store,
+        documents_fields_counts_store,
+        postings_lists_store,
+        docs_words_store,
+    )?;
+
+    Ok(())
+}