MeiliSearch/milli/src/search/mod.rs

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use std::borrow::Cow;
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use std::collections::hash_map::{Entry, HashMap};
use std::fmt;
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use std::mem::take;
use std::result::Result as StdResult;
use std::str::Utf8Error;
use std::time::Instant;
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use charabia::TokenizerBuilder;
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use distinct::{Distinct, DocIter, FacetDistinct, NoopDistinct};
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use fst::automaton::Str;
use fst::{Automaton, IntoStreamer, Streamer};
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use levenshtein_automata::{LevenshteinAutomatonBuilder as LevBuilder, DFA};
use log::debug;
use once_cell::sync::Lazy;
use roaring::bitmap::RoaringBitmap;
pub use self::facet::{FacetDistribution, FacetNumberIter, Filter, DEFAULT_VALUES_PER_FACET};
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use self::fst_utils::{Complement, Intersection, StartsWith, Union};
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pub use self::matches::{
FormatOptions, MatchBounds, Matcher, MatcherBuilder, MatchingWord, MatchingWords,
};
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use self::query_tree::QueryTreeBuilder;
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use crate::error::UserError;
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use crate::search::criteria::r#final::{Final, FinalResult};
use crate::{AscDesc, Criterion, DocumentId, Index, Member, Result};
// Building these factories is not free.
static LEVDIST0: Lazy<LevBuilder> = Lazy::new(|| LevBuilder::new(0, true));
static LEVDIST1: Lazy<LevBuilder> = Lazy::new(|| LevBuilder::new(1, true));
static LEVDIST2: Lazy<LevBuilder> = Lazy::new(|| LevBuilder::new(2, true));
mod criteria;
mod distinct;
mod facet;
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mod fst_utils;
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mod matches;
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mod query_tree;
pub struct Search<'a> {
query: Option<String>,
// this should be linked to the String in the query
filter: Option<Filter<'a>>,
offset: usize,
limit: usize,
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sort_criteria: Option<Vec<AscDesc>>,
optional_words: bool,
authorize_typos: bool,
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words_limit: usize,
rtxn: &'a heed::RoTxn<'a>,
index: &'a Index,
}
impl<'a> Search<'a> {
pub fn new(rtxn: &'a heed::RoTxn, index: &'a Index) -> Search<'a> {
Search {
query: None,
filter: None,
offset: 0,
limit: 20,
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sort_criteria: None,
optional_words: true,
authorize_typos: true,
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words_limit: 10,
rtxn,
index,
}
}
pub fn query(&mut self, query: impl Into<String>) -> &mut Search<'a> {
self.query = Some(query.into());
self
}
pub fn offset(&mut self, offset: usize) -> &mut Search<'a> {
self.offset = offset;
self
}
pub fn limit(&mut self, limit: usize) -> &mut Search<'a> {
self.limit = limit;
self
}
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pub fn sort_criteria(&mut self, criteria: Vec<AscDesc>) -> &mut Search<'a> {
self.sort_criteria = Some(criteria);
self
}
pub fn optional_words(&mut self, value: bool) -> &mut Search<'a> {
self.optional_words = value;
self
}
pub fn authorize_typos(&mut self, value: bool) -> &mut Search<'a> {
self.authorize_typos = value;
self
}
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pub fn words_limit(&mut self, value: usize) -> &mut Search<'a> {
self.words_limit = value;
self
}
pub fn filter(&mut self, condition: Filter<'a>) -> &mut Search<'a> {
self.filter = Some(condition);
self
}
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fn is_typo_authorized(&self) -> Result<bool> {
let index_authorizes_typos = self.index.authorize_typos(self.rtxn)?;
// only authorize typos if both the index and the query allow it.
Ok(self.authorize_typos && index_authorizes_typos)
}
pub fn execute(&self) -> Result<SearchResult> {
// We create the query tree by spliting the query into tokens.
let before = Instant::now();
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let (query_tree, primitive_query, matching_words) = match self.query.as_ref() {
Some(query) => {
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let mut builder = QueryTreeBuilder::new(self.rtxn, self.index)?;
builder.optional_words(self.optional_words);
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builder.authorize_typos(self.is_typo_authorized()?);
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builder.words_limit(self.words_limit);
// We make sure that the analyzer is aware of the stop words
// this ensures that the query builder is able to properly remove them.
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let mut tokbuilder = TokenizerBuilder::new();
let stop_words = self.index.stop_words(self.rtxn)?;
if let Some(ref stop_words) = stop_words {
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tokbuilder.stop_words(stop_words);
}
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let tokenizer = tokbuilder.build();
let tokens = tokenizer.tokenize(query);
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builder
.build(tokens)?
.map_or((None, None, None), |(qt, pq, mw)| (Some(qt), Some(pq), Some(mw)))
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}
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None => (None, None, None),
};
debug!("query tree: {:?} took {:.02?}", query_tree, before.elapsed());
// We create the original candidates with the facet conditions results.
let before = Instant::now();
let filtered_candidates = match &self.filter {
Some(condition) => Some(condition.evaluate(self.rtxn, self.index)?),
None => None,
};
debug!("facet candidates: {:?} took {:.02?}", filtered_candidates, before.elapsed());
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// We check that we are allowed to use the sort criteria, we check
// that they are declared in the sortable fields.
if let Some(sort_criteria) = &self.sort_criteria {
let sortable_fields = self.index.sortable_fields(self.rtxn)?;
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for asc_desc in sort_criteria {
match asc_desc.member() {
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Member::Field(ref field) if !crate::is_faceted(field, &sortable_fields) => {
return Err(UserError::InvalidSortableAttribute {
field: field.to_string(),
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valid_fields: sortable_fields.into_iter().collect(),
})?
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}
Member::Geo(_) if !sortable_fields.contains("_geo") => {
return Err(UserError::InvalidSortableAttribute {
field: "_geo".to_string(),
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valid_fields: sortable_fields.into_iter().collect(),
})?
}
_ => (),
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}
}
}
// We check that the sort ranking rule exists and throw an
// error if we try to use it and that it doesn't.
let sort_ranking_rule_missing = !self.index.criteria(self.rtxn)?.contains(&Criterion::Sort);
let empty_sort_criteria = self.sort_criteria.as_ref().map_or(true, |s| s.is_empty());
if sort_ranking_rule_missing && !empty_sort_criteria {
return Err(UserError::SortRankingRuleMissing.into());
}
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let criteria_builder = criteria::CriteriaBuilder::new(self.rtxn, self.index)?;
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let criteria = criteria_builder.build(
query_tree,
primitive_query,
filtered_candidates,
self.sort_criteria.clone(),
)?;
match self.index.distinct_field(self.rtxn)? {
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None => self.perform_sort(NoopDistinct, matching_words.unwrap_or_default(), criteria),
Some(name) => {
let field_ids_map = self.index.fields_ids_map(self.rtxn)?;
match field_ids_map.id(name) {
Some(fid) => {
let distinct = FacetDistinct::new(fid, self.index, self.rtxn);
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self.perform_sort(distinct, matching_words.unwrap_or_default(), criteria)
}
None => Ok(SearchResult::default()),
}
}
}
}
fn perform_sort<D: Distinct>(
&self,
mut distinct: D,
matching_words: MatchingWords,
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mut criteria: Final,
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) -> Result<SearchResult> {
let mut offset = self.offset;
let mut initial_candidates = RoaringBitmap::new();
let mut excluded_candidates = self.index.soft_deleted_documents_ids(self.rtxn)?;
let mut documents_ids = Vec::new();
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while let Some(FinalResult { candidates, bucket_candidates, .. }) =
criteria.next(&excluded_candidates)?
{
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debug!("Number of candidates found {}", candidates.len());
let excluded = take(&mut excluded_candidates);
let mut candidates = distinct.distinct(candidates, excluded);
initial_candidates |= bucket_candidates;
if offset != 0 {
let discarded = candidates.by_ref().take(offset).count();
offset = offset.saturating_sub(discarded);
}
for candidate in candidates.by_ref().take(self.limit - documents_ids.len()) {
documents_ids.push(candidate?);
}
excluded_candidates |= candidates.into_excluded();
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if documents_ids.len() == self.limit {
break;
}
}
Ok(SearchResult {
matching_words,
candidates: initial_candidates - excluded_candidates,
documents_ids,
})
}
}
impl fmt::Debug for Search<'_> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let Search {
query,
filter,
offset,
limit,
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sort_criteria,
optional_words,
authorize_typos,
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words_limit,
rtxn: _,
index: _,
} = self;
f.debug_struct("Search")
.field("query", query)
.field("filter", filter)
.field("offset", offset)
.field("limit", limit)
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.field("sort_criteria", sort_criteria)
.field("optional_words", optional_words)
.field("authorize_typos", authorize_typos)
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.field("words_limit", words_limit)
.finish()
}
}
#[derive(Default)]
pub struct SearchResult {
pub matching_words: MatchingWords,
pub candidates: RoaringBitmap,
// TODO those documents ids should be associated with their criteria scores.
pub documents_ids: Vec<DocumentId>,
}
pub type WordDerivationsCache = HashMap<(String, bool, u8), Vec<(String, u8)>>;
pub fn word_derivations<'c>(
word: &str,
is_prefix: bool,
max_typo: u8,
fst: &fst::Set<Cow<[u8]>>,
cache: &'c mut WordDerivationsCache,
) -> StdResult<&'c [(String, u8)], Utf8Error> {
match cache.entry((word.to_string(), is_prefix, max_typo)) {
Entry::Occupied(entry) => Ok(entry.into_mut()),
Entry::Vacant(entry) => {
let mut derived_words = Vec::new();
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if max_typo == 0 {
if is_prefix {
let prefix = Str::new(word).starts_with();
let mut stream = fst.search(prefix).into_stream();
while let Some(word) = stream.next() {
let word = std::str::from_utf8(word)?;
derived_words.push((word.to_string(), 0));
}
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} else if fst.contains(word) {
derived_words.push((word.to_string(), 0));
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}
} else {
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if max_typo == 1 {
let dfa = build_dfa(word, 1, is_prefix);
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let starts = StartsWith(Str::new(get_first(word)));
let mut stream =
fst.search_with_state(Intersection(starts, &dfa)).into_stream();
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while let Some((word, state)) = stream.next() {
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let word = std::str::from_utf8(word)?;
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let d = dfa.distance(state.1);
derived_words.push((word.to_string(), d.to_u8()));
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}
} else {
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let starts = StartsWith(Str::new(get_first(word)));
let first = Intersection(build_dfa(word, 1, is_prefix), Complement(&starts));
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let second_dfa = build_dfa(word, 2, is_prefix);
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let second = Intersection(&second_dfa, &starts);
let automaton = Union(first, &second);
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let mut stream = fst.search_with_state(automaton).into_stream();
while let Some((found_word, state)) = stream.next() {
let found_word = std::str::from_utf8(found_word)?;
// in the case the typo is on the first letter, we know the number of typo
// is two
if get_first(found_word) != get_first(word) {
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derived_words.push((found_word.to_string(), 2));
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} else {
// Else, we know that it is the second dfa that matched and compute the
// correct distance
let d = second_dfa.distance((state.1).0);
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derived_words.push((found_word.to_string(), d.to_u8()));
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}
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}
}
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}
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Ok(entry.insert(derived_words))
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}
}
}
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fn get_first(s: &str) -> &str {
match s.chars().next() {
Some(c) => &s[..c.len_utf8()],
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None => panic!("unexpected empty query"),
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}
}
pub fn build_dfa(word: &str, typos: u8, is_prefix: bool) -> DFA {
let lev = match typos {
0 => &LEVDIST0,
1 => &LEVDIST1,
_ => &LEVDIST2,
};
if is_prefix {
lev.build_prefix_dfa(word)
} else {
lev.build_dfa(word)
}
}
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#[cfg(test)]
mod test {
use super::*;
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use crate::index::tests::TempIndex;
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#[test]
fn test_is_authorized_typos() {
let index = TempIndex::new();
let mut txn = index.write_txn().unwrap();
let mut search = Search::new(&txn, &index);
// default is authorized
assert!(search.is_typo_authorized().unwrap());
search.authorize_typos(false);
assert!(!search.is_typo_authorized().unwrap());
index.put_authorize_typos(&mut txn, false).unwrap();
txn.commit().unwrap();
let txn = index.read_txn().unwrap();
let mut search = Search::new(&txn, &index);
assert!(!search.is_typo_authorized().unwrap());
search.authorize_typos(true);
assert!(!search.is_typo_authorized().unwrap());
}
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#[test]
fn test_one_typos_tolerance() {
let fst = fst::Set::from_iter(["zealand"].iter()).unwrap().map_data(Cow::Owned).unwrap();
let mut cache = HashMap::new();
let found = word_derivations("zealend", false, 1, &fst, &mut cache).unwrap();
assert_eq!(found, &[("zealand".to_string(), 1)]);
}
#[test]
fn test_one_typos_first_letter() {
let fst = fst::Set::from_iter(["zealand"].iter()).unwrap().map_data(Cow::Owned).unwrap();
let mut cache = HashMap::new();
let found = word_derivations("sealand", false, 1, &fst, &mut cache).unwrap();
assert_eq!(found, &[]);
}
#[test]
fn test_two_typos_tolerance() {
let fst = fst::Set::from_iter(["zealand"].iter()).unwrap().map_data(Cow::Owned).unwrap();
let mut cache = HashMap::new();
let found = word_derivations("zealemd", false, 2, &fst, &mut cache).unwrap();
assert_eq!(found, &[("zealand".to_string(), 2)]);
}
#[test]
fn test_two_typos_first_letter() {
let fst = fst::Set::from_iter(["zealand"].iter()).unwrap().map_data(Cow::Owned).unwrap();
let mut cache = HashMap::new();
let found = word_derivations("sealand", false, 2, &fst, &mut cache).unwrap();
assert_eq!(found, &[("zealand".to_string(), 2)]);
}
#[test]
fn test_prefix() {
let fst = fst::Set::from_iter(["zealand"].iter()).unwrap().map_data(Cow::Owned).unwrap();
let mut cache = HashMap::new();
let found = word_derivations("ze", true, 0, &fst, &mut cache).unwrap();
assert_eq!(found, &[("zealand".to_string(), 0)]);
}
#[test]
fn test_bad_prefix() {
let fst = fst::Set::from_iter(["zealand"].iter()).unwrap().map_data(Cow::Owned).unwrap();
let mut cache = HashMap::new();
let found = word_derivations("se", true, 0, &fst, &mut cache).unwrap();
assert_eq!(found, &[]);
}
#[test]
fn test_prefix_with_typo() {
let fst = fst::Set::from_iter(["zealand"].iter()).unwrap().map_data(Cow::Owned).unwrap();
let mut cache = HashMap::new();
let found = word_derivations("zae", true, 1, &fst, &mut cache).unwrap();
assert_eq!(found, &[("zealand".to_string(), 1)]);
}
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}