Merge #473

473: set minimum word len for typos r=MarinPostma a=MarinPostma

this PR allows the configuration on the minimum word length for typos.

The default values are the same as previously.

## steps
- [x] introduce settings for the minimum word length for 1 and 2 typos
- [x] update the settings update flow to set this setting
- [x] create a structure `TypoConfig` to configure typo tolerance in the query builder
- [x] in `typo`, use the configuration to create the appropriate query tree node.
- [x] extend `Context` to return the setting for minimum word length for typos
- [x] return correct error message for wrong settings.
- [x] merge #469 

Co-authored-by: ad hoc <postma.marin@protonmail.com>

milli/src/error.rs

@@ -72,6 +72,7 @@ pub enum UserError {
     SerdeJson(serde_json::Error),
     SortError(SortError),
     UnknownInternalDocumentId { document_id: DocumentId },
+    InvalidMinTypoWordLenSetting(u8, u8),
 }
 
 impl From<io::Error> for Error {
@@ -291,6 +292,7 @@ ranking rules settings to use the sort parameter at search time.",
             Self::UnknownInternalDocumentId { document_id } => {
                 write!(f, "An unknown internal document id have been used: `{}`.", document_id)
             }
+            Self::InvalidMinTypoWordLenSetting(one, two) => write!(f, "`minWordSizeForTypos` setting is invalid. `oneTypo` and `twoTypos` fields should be between `0` and `255`, and `twoTypos` should be greater or equals to `oneTypo` but found `oneTypo: {}` and twoTypos: {}`.", one, two),
         }
     }
 }

milli/src/index.rs

@@ -23,6 +23,9 @@ use crate::{
     Search, StrBEU32Codec, StrStrU8Codec, BEU32,
 };
 
+pub const DEFAULT_MIN_WORD_LEN_ONE_TYPO: u8 = 5;
+pub const DEFAULT_MIN_WORD_LEN_TWO_TYPOS: u8 = 9;
+
 pub mod main_key {
     pub const CRITERIA_KEY: &str = "criteria";
     pub const DISPLAYED_FIELDS_KEY: &str = "displayed-fields";
@@ -47,6 +50,8 @@ pub mod main_key {
     pub const CREATED_AT_KEY: &str = "created-at";
     pub const UPDATED_AT_KEY: &str = "updated-at";
     pub const AUTHORIZE_TYPOS: &str = "authorize-typos";
+    pub const ONE_TYPO_WORD_LEN: &str = "one-typo-word-len";
+    pub const TWO_TYPOS_WORD_LEN: &str = "two-typos-word-len";
 }
 
 pub mod db_name {
@@ -886,6 +891,42 @@ impl Index {
 
         Ok(())
     }
+
+    pub fn min_word_len_one_typo(&self, txn: &RoTxn) -> heed::Result<u8> {
+        // It is not possible to put a bool in heed with OwnedType, so we put a u8 instead. We
+        // identify 0 as being false, and anything else as true. The absence of a value is true,
+        // because by default, we authorize typos.
+        Ok(self
+            .main
+            .get::<_, Str, OwnedType<u8>>(txn, main_key::ONE_TYPO_WORD_LEN)?
+            .unwrap_or(DEFAULT_MIN_WORD_LEN_ONE_TYPO))
+    }
+
+    pub(crate) fn put_min_word_len_one_typo(&self, txn: &mut RwTxn, val: u8) -> heed::Result<()> {
+        // It is not possible to put a bool in heed with OwnedType, so we put a u8 instead. We
+        // identify 0 as being false, and anything else as true. The absence of a value is true,
+        // because by default, we authorize typos.
+        self.main.put::<_, Str, OwnedType<u8>>(txn, main_key::ONE_TYPO_WORD_LEN, &val)?;
+        Ok(())
+    }
+
+    pub fn min_word_len_two_typos(&self, txn: &RoTxn) -> heed::Result<u8> {
+        // It is not possible to put a bool in heed with OwnedType, so we put a u8 instead. We
+        // identify 0 as being false, and anything else as true. The absence of a value is true,
+        // because by default, we authorize typos.
+        Ok(self
+            .main
+            .get::<_, Str, OwnedType<u8>>(txn, main_key::TWO_TYPOS_WORD_LEN)?
+            .unwrap_or(DEFAULT_MIN_WORD_LEN_TWO_TYPOS))
+    }
+
+    pub(crate) fn put_min_word_len_two_typos(&self, txn: &mut RwTxn, val: u8) -> heed::Result<()> {
+        // It is not possible to put a bool in heed with OwnedType, so we put a u8 instead. We
+        // identify 0 as being false, and anything else as true. The absence of a value is true,
+        // because by default, we authorize typos.
+        self.main.put::<_, Str, OwnedType<u8>>(txn, main_key::TWO_TYPOS_WORD_LEN, &val)?;
+        Ok(())
+    }
 }
 
 #[cfg(test)]
@@ -896,6 +937,7 @@ pub(crate) mod tests {
     use maplit::btreemap;
     use tempfile::TempDir;
 
+    use crate::index::{DEFAULT_MIN_WORD_LEN_ONE_TYPO, DEFAULT_MIN_WORD_LEN_TWO_TYPOS};
     use crate::update::{IndexDocuments, IndexDocumentsConfig, IndexerConfig};
     use crate::Index;
 
@@ -1023,4 +1065,22 @@ pub(crate) mod tests {
         let txn = index.read_txn().unwrap();
         assert!(!index.authorize_typos(&txn).unwrap());
     }
+
+    #[test]
+    fn set_min_word_len_for_typos() {
+        let index = TempIndex::new();
+        let mut txn = index.write_txn().unwrap();
+
+        assert_eq!(index.min_word_len_one_typo(&txn).unwrap(), DEFAULT_MIN_WORD_LEN_ONE_TYPO);
+        assert_eq!(index.min_word_len_two_typos(&txn).unwrap(), DEFAULT_MIN_WORD_LEN_TWO_TYPOS);
+
+        index.put_min_word_len_one_typo(&mut txn, 3).unwrap();
+        index.put_min_word_len_two_typos(&mut txn, 15).unwrap();
+
+        txn.commit().unwrap();
+
+        let txn = index.read_txn().unwrap();
+        assert_eq!(index.min_word_len_one_typo(&txn).unwrap(), 3);
+        assert_eq!(index.min_word_len_two_typos(&txn).unwrap(), 15);
+    }
 }

milli/src/search/query_tree.rs

@@ -155,6 +155,8 @@ trait Context {
             None => Ok(None),
         }
     }
+    /// Returns the minimum word len for 1 and 2 typos.
+    fn min_word_len_for_typo(&self) -> heed::Result<(u8, u8)>;
 }
 
 /// The query tree builder is the interface to build a query tree.
@@ -178,6 +180,12 @@ impl<'a> Context for QueryTreeBuilder<'a> {
     fn word_documents_count(&self, word: &str) -> heed::Result<Option<u64>> {
         self.index.word_documents_count(self.rtxn, word)
     }
+
+    fn min_word_len_for_typo(&self) -> heed::Result<(u8, u8)> {
+        let one = self.index.min_word_len_one_typo(&self.rtxn)?;
+        let two = self.index.min_word_len_two_typos(&self.rtxn)?;
+        Ok((one, two))
+    }
 }
 
 impl<'a> QueryTreeBuilder<'a> {
@@ -256,14 +264,24 @@ fn split_best_frequency(ctx: &impl Context, word: &str) -> heed::Result<Option<O
     Ok(best.map(|(_, left, right)| Operation::Phrase(vec![left.to_string(), right.to_string()])))
 }
 
+#[derive(Clone)]
+pub struct TypoConfig {
+    pub max_typos: u8,
+    pub word_len_one_typo: u8,
+    pub word_len_two_typo: u8,
+}
+
 /// Return the `QueryKind` of a word depending on `authorize_typos`
 /// and the provided word length.
-fn typos(word: String, authorize_typos: bool, max_typos: u8) -> QueryKind {
+fn typos(word: String, authorize_typos: bool, config: TypoConfig) -> QueryKind {
     if authorize_typos {
-        match word.chars().count() {
-            0..=4 => QueryKind::exact(word),
-            5..=8 => QueryKind::tolerant(1.min(max_typos), word),
-            _ => QueryKind::tolerant(2.min(max_typos), word),
+        let count = word.chars().count().min(u8::MAX as usize) as u8;
+        if count < config.word_len_one_typo {
+            QueryKind::exact(word)
+        } else if count < config.word_len_two_typo {
+            QueryKind::tolerant(1.min(config.max_typos), word)
+        } else {
+            QueryKind::tolerant(2.min(config.max_typos), word)
         }
     } else {
         QueryKind::exact(word)
@@ -314,9 +332,11 @@ fn create_query_tree(
                 if let Some(child) = split_best_frequency(ctx, &word)? {
                     children.push(child);
                 }
+                let (word_len_one_typo, word_len_two_typo) = ctx.min_word_len_for_typo()?;
+                let config = TypoConfig { max_typos: 2, word_len_one_typo, word_len_two_typo };
                 children.push(Operation::Query(Query {
                     prefix,
-                    kind: typos(word, authorize_typos, 2),
+                    kind: typos(word, authorize_typos, config),
                 }));
                 Ok(Operation::or(false, children))
             }
@@ -363,9 +383,13 @@ fn create_query_tree(
                                 .collect();
                             let mut operations = synonyms(ctx, &words)?.unwrap_or_default();
                             let concat = words.concat();
+                            let (word_len_one_typo, word_len_two_typo) =
+                                ctx.min_word_len_for_typo()?;
+                            let config =
+                                TypoConfig { max_typos: 1, word_len_one_typo, word_len_two_typo };
                             let query = Query {
                                 prefix: is_prefix,
-                                kind: typos(concat, authorize_typos, 1),
+                                kind: typos(concat, authorize_typos, config),
                             };
                             operations.push(Operation::Query(query));
                             and_op_children.push(Operation::or(false, operations));
@@ -541,6 +565,7 @@ mod test {
     use rand::{Rng, SeedableRng};
 
     use super::*;
+    use crate::index::{DEFAULT_MIN_WORD_LEN_ONE_TYPO, DEFAULT_MIN_WORD_LEN_TWO_TYPOS};
 
     #[derive(Debug)]
     struct TestContext {
@@ -576,6 +601,10 @@ mod test {
             let words: Vec<_> = words.iter().map(|s| s.as_ref().to_owned()).collect();
             Ok(self.synonyms.get(&words).cloned())
         }
+
+        fn min_word_len_for_typo(&self) -> heed::Result<(u8, u8)> {
+            Ok((DEFAULT_MIN_WORD_LEN_ONE_TYPO, DEFAULT_MIN_WORD_LEN_TWO_TYPOS))
+        }
     }
 
     impl Default for TestContext {
@@ -1193,4 +1222,24 @@ mod test {
 
         assert_eq!(expected, query_tree);
     }
+
+    #[test]
+    fn test_min_word_len_typo() {
+        let config = TypoConfig { max_typos: 2, word_len_one_typo: 5, word_len_two_typo: 7 };
+
+        assert_eq!(
+            typos("hello".to_string(), true, config.clone()),
+            QueryKind::Tolerant { typo: 1, word: "hello".to_string() }
+        );
+
+        assert_eq!(
+            typos("hell".to_string(), true, config.clone()),
+            QueryKind::exact("hell".to_string())
+        );
+
+        assert_eq!(
+            typos("verylongword".to_string(), true, config.clone()),
+            QueryKind::Tolerant { typo: 2, word: "verylongword".to_string() }
+        );
+    }
 }

milli/src/update/settings.rs

@@ -14,7 +14,7 @@ use crate::update::index_documents::IndexDocumentsMethod;
 use crate::update::{ClearDocuments, IndexDocuments, UpdateIndexingStep};
 use crate::{FieldsIdsMap, Index, Result};
 
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone, PartialEq, Copy)]
 pub enum Setting<T> {
     Set(T),
     Reset,
@@ -90,6 +90,8 @@ pub struct Settings<'a, 't, 'u, 'i> {
     synonyms: Setting<HashMap<String, Vec<String>>>,
     primary_key: Setting<String>,
     authorize_typos: Setting<bool>,
+    min_word_len_two_typos: Setting<u8>,
+    min_word_len_one_typo: Setting<u8>,
 }
 
 impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
@@ -112,6 +114,8 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
             primary_key: Setting::NotSet,
             authorize_typos: Setting::NotSet,
             indexer_config,
+            min_word_len_two_typos: Setting::Reset,
+            min_word_len_one_typo: Setting::Reset,
         }
     }
 
@@ -196,6 +200,22 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
         self.authorize_typos = Setting::Reset;
     }
 
+    pub fn set_min_word_len_two_typos(&mut self, val: u8) {
+        self.min_word_len_two_typos = Setting::Set(val);
+    }
+
+    pub fn reset_min_word_len_two_typos(&mut self) {
+        self.min_word_len_two_typos = Setting::Reset;
+    }
+
+    pub fn set_min_word_len_one_typo(&mut self, val: u8) {
+        self.min_word_len_one_typo = Setting::Set(val);
+    }
+
+    pub fn reset_min_word_len_one_typo(&mut self) {
+        self.min_word_len_one_typo = Setting::Reset;
+    }
+
     fn reindex<F>(&mut self, cb: &F, old_fields_ids_map: FieldsIdsMap) -> Result<()>
     where
         F: Fn(UpdateIndexingStep) + Sync,
@@ -474,6 +494,38 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
         }
     }
 
+    fn update_min_typo_word_len(&mut self) -> Result<()> {
+        match (self.min_word_len_one_typo, self.min_word_len_two_typos) {
+            (Setting::Set(one), Setting::Set(two)) => {
+                if one > two {
+                    return Err(UserError::InvalidMinTypoWordLenSetting(one, two).into());
+                } else {
+                    self.index.put_min_word_len_one_typo(&mut self.wtxn, one)?;
+                    self.index.put_min_word_len_two_typos(&mut self.wtxn, two)?;
+                }
+            }
+            (Setting::Set(one), _) => {
+                let two = self.index.min_word_len_two_typos(&self.wtxn)?;
+                if one > two {
+                    return Err(UserError::InvalidMinTypoWordLenSetting(one, two).into());
+                } else {
+                    self.index.put_min_word_len_one_typo(&mut self.wtxn, one)?;
+                }
+            }
+            (_, Setting::Set(two)) => {
+                let one = self.index.min_word_len_one_typo(&self.wtxn)?;
+                if one > two {
+                    return Err(UserError::InvalidMinTypoWordLenSetting(one, two).into());
+                } else {
+                    self.index.put_min_word_len_two_typos(&mut self.wtxn, two)?;
+                }
+            }
+            _ => (),
+        }
+
+        Ok(())
+    }
+
     pub fn execute<F>(mut self, progress_callback: F) -> Result<()>
     where
         F: Fn(UpdateIndexingStep) + Sync,
@@ -490,6 +542,7 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
         self.update_criteria()?;
         self.update_primary_key()?;
         self.update_authorize_typos()?;
+        self.update_min_typo_word_len()?;
 
         // If there is new faceted fields we indicate that we must reindex as we must
         // index new fields as facets. It means that the distinct attribute,
@@ -1233,4 +1286,37 @@ mod tests {
         builder.execute(|_| ()).unwrap();
         assert!(!index.authorize_typos(&txn).unwrap());
     }
+
+    #[test]
+    fn update_min_word_len_for_typo() {
+        let index = TempIndex::new();
+        let config = IndexerConfig::default();
+
+        // Set the genres setting
+        let mut txn = index.write_txn().unwrap();
+        let mut builder = Settings::new(&mut txn, &index, &config);
+        builder.set_min_word_len_one_typo(8);
+        builder.set_min_word_len_two_typos(8);
+        builder.execute(|_| ()).unwrap();
+
+        txn.commit().unwrap();
+
+        let txn = index.read_txn().unwrap();
+
+        assert_eq!(index.min_word_len_one_typo(&txn).unwrap(), 8);
+        assert_eq!(index.min_word_len_two_typos(&txn).unwrap(), 8);
+    }
+
+    #[test]
+    fn update_invalid_min_word_len_for_typo() {
+        let index = TempIndex::new();
+        let config = IndexerConfig::default();
+
+        // Set the genres setting
+        let mut txn = index.write_txn().unwrap();
+        let mut builder = Settings::new(&mut txn, &index, &config);
+        builder.set_min_word_len_one_typo(10);
+        builder.set_min_word_len_two_typos(7);
+        assert!(builder.execute(|_| ()).is_err());
+    }
 }

milli/tests/search/mod.rs

@@ -16,6 +16,7 @@ mod distinct;
 mod filters;
 mod query_criteria;
 mod sort;
+mod typo_tolerance;
 
 pub const TEST_QUERY: &'static str = "hello world america";
 

milli/tests/search/typo_tolerance.rs

@@ -0,0 +1,95 @@
+use milli::update::{IndexerConfig, Settings};
+use milli::{Criterion, Search};
+use Criterion::*;
+
+#[test]
+fn test_typo_tolerance_one_typo() {
+    let criteria = [Typo];
+    let index = super::setup_search_index_with_criteria(&criteria);
+
+    // basic typo search with default typo settings
+    {
+        let txn = index.read_txn().unwrap();
+
+        let mut search = Search::new(&txn, &index);
+        search.query("zeal");
+        search.limit(10);
+        search.authorize_typos(true);
+        search.optional_words(true);
+
+        let result = search.execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 1);
+
+        let mut search = Search::new(&txn, &index);
+        search.query("zean");
+        search.limit(10);
+        search.authorize_typos(true);
+        search.optional_words(true);
+
+        let result = search.execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 0);
+    }
+
+    let mut txn = index.write_txn().unwrap();
+
+    let config = IndexerConfig::default();
+    let mut builder = Settings::new(&mut txn, &index, &config);
+    builder.set_min_word_len_one_typo(4);
+    builder.execute(|_| ()).unwrap();
+
+    // typo is now supported for 4 letters words
+    let mut search = Search::new(&txn, &index);
+    search.query("zean");
+    search.limit(10);
+    search.authorize_typos(true);
+    search.optional_words(true);
+
+    let result = search.execute().unwrap();
+    assert_eq!(result.documents_ids.len(), 1);
+}
+
+#[test]
+fn test_typo_tolerance_two_typo() {
+    let criteria = [Typo];
+    let index = super::setup_search_index_with_criteria(&criteria);
+
+    // basic typo search with default typo settings
+    {
+        let txn = index.read_txn().unwrap();
+
+        let mut search = Search::new(&txn, &index);
+        search.query("zealand");
+        search.limit(10);
+        search.authorize_typos(true);
+        search.optional_words(true);
+
+        let result = search.execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 1);
+
+        let mut search = Search::new(&txn, &index);
+        search.query("zealemd");
+        search.limit(10);
+        search.authorize_typos(true);
+        search.optional_words(true);
+
+        let result = search.execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 0);
+    }
+
+    let mut txn = index.write_txn().unwrap();
+
+    let config = IndexerConfig::default();
+    let mut builder = Settings::new(&mut txn, &index, &config);
+    builder.set_min_word_len_two_typos(7);
+    builder.execute(|_| ()).unwrap();
+
+    // typo is now supported for 4 letters words
+    let mut search = Search::new(&txn, &index);
+    search.query("zealemd");
+    search.limit(10);
+    search.authorize_typos(true);
+    search.optional_words(true);
+
+    let result = search.execute().unwrap();
+    assert_eq!(result.documents_ids.len(), 1);
+}