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Introduce bucket_sort_with_distinct function

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This commit is contained in:
Clément Renault 2019-12-11 17:36:53 +01:00
parent 248ccfc0d8
commit 86ee0cbd6e
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GPG Key ID: 0151CDAB43460DAE
5 changed files with 272 additions and 329 deletions
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292
meilisearch-core/src/automaton/mod.rs
View File

@ -1,17 +1,7 @@
mod dfa;
mod query_enhancer;
use std::cmp::Reverse;
use std::{cmp, fmt, vec};
use fst::{IntoStreamer, Streamer};
use levenshtein_automata::DFA;
use meilisearch_tokenizer::{is_cjk, split_query_string};
use log::debug;
use crate::database::MainT;
use crate::error::MResult;
use crate::store;
use meilisearch_tokenizer::is_cjk;
pub use self::dfa::{build_dfa, build_prefix_dfa, build_exact_dfa};
pub use self::query_enhancer::QueryEnhancer;
@ -19,122 +9,6 @@ pub use self::query_enhancer::QueryEnhancerBuilder;
pub const NGRAMS: usize = 3;
pub struct AutomatonProducer {
automatons: Vec<AutomatonGroup>,
}
impl AutomatonProducer {
pub fn new(
reader: &heed::RoTxn<MainT>,
query: &str,
main_store: store::Main,
postings_list_store: store::PostingsLists,
synonyms_store: store::Synonyms,
) -> MResult<(AutomatonProducer, QueryEnhancer)> {
let (automatons, query_enhancer) = generate_automatons(
reader,
query,
main_store,
postings_list_store,
synonyms_store,
)?;
for (i, group) in automatons.iter().enumerate() {
debug!("all automatons: group {} automatons {:?}", i, group.automatons);
}
Ok((AutomatonProducer { automatons }, query_enhancer))
}
pub fn into_iter(self) -> vec::IntoIter<AutomatonGroup> {
self.automatons.into_iter()
}
}
#[derive(Debug)]
pub struct AutomatonGroup {
pub is_phrase_query: bool,
pub automatons: Vec<Automaton>,
}
impl AutomatonGroup {
fn normal(automatons: Vec<Automaton>) -> AutomatonGroup {
AutomatonGroup {
is_phrase_query: false,
automatons,
}
}
fn phrase_query(automatons: Vec<Automaton>) -> AutomatonGroup {
AutomatonGroup {
is_phrase_query: true,
automatons,
}
}
}
pub struct Automaton {
pub index: usize,
pub ngram: usize,
pub query_len: usize,
pub is_exact: bool,
pub is_prefix: bool,
pub query: String,
}
impl fmt::Debug for Automaton {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Automaton")
.field("index", &self.index)
.field("query", &self.query)
.field("is_prefix", &self.is_prefix)
.finish()
}
}
impl Automaton {
pub fn dfa(&self) -> DFA {
if self.is_prefix {
build_prefix_dfa(&self.query)
} else {
build_dfa(&self.query)
}
}
fn exact(index: usize, ngram: usize, query: &str) -> Automaton {
Automaton {
index,
ngram,
query_len: query.len(),
is_exact: true,
is_prefix: false,
query: query.to_string(),
}
}
fn prefix_exact(index: usize, ngram: usize, query: &str) -> Automaton {
Automaton {
index,
ngram,
query_len: query.len(),
is_exact: true,
is_prefix: true,
query: query.to_string(),
}
}
fn non_exact(index: usize, ngram: usize, query: &str) -> Automaton {
Automaton {
index,
ngram,
query_len: query.len(),
is_exact: false,
is_prefix: false,
query: query.to_string(),
}
}
}
pub fn normalize_str(string: &str) -> String {
let mut string = string.to_lowercase();
@ -144,167 +18,3 @@ pub fn normalize_str(string: &str) -> String {
string
}
pub fn split_best_frequency<'a>(
reader: &heed::RoTxn<MainT>,
word: &'a str,
postings_lists_store: store::PostingsLists,
) -> MResult<Option<(&'a str, &'a str)>> {
let chars = word.char_indices().skip(1);
let mut best = None;
for (i, _) in chars {
let (left, right) = word.split_at(i);
let left_freq = postings_lists_store
.postings_list(reader, left.as_ref())?
.map_or(0, |i| i.len());
let right_freq = postings_lists_store
.postings_list(reader, right.as_ref())?
.map_or(0, |i| i.len());
let min_freq = cmp::min(left_freq, right_freq);
if min_freq != 0 && best.map_or(true, |(old, _, _)| min_freq > old) {
best = Some((min_freq, left, right));
}
}
Ok(best.map(|(_, l, r)| (l, r)))
}
fn generate_automatons(
reader: &heed::RoTxn<MainT>,
query: &str,
main_store: store::Main,
postings_lists_store: store::PostingsLists,
synonym_store: store::Synonyms,
) -> MResult<(Vec<AutomatonGroup>, QueryEnhancer)> {
let has_end_whitespace = query.chars().last().map_or(false, char::is_whitespace);
let query_words: Vec<_> = split_query_string(query).map(str::to_lowercase).collect();
let synonyms = match main_store.synonyms_fst(reader)? {
Some(synonym) => synonym,
None => fst::Set::default(),
};
let mut automaton_index = 0;
let mut automatons = Vec::new();
let mut enhancer_builder = QueryEnhancerBuilder::new(&query_words);
// We must not declare the original words to the query enhancer
// *but* we need to push them in the automatons list first
let mut original_automatons = Vec::new();
let mut original_words = query_words.iter().peekable();
while let Some(word) = original_words.next() {
let has_following_word = original_words.peek().is_some();
let not_prefix_dfa = has_following_word || has_end_whitespace || word.chars().all(is_cjk);
let automaton = if not_prefix_dfa {
Automaton::exact(automaton_index, 1, word)
} else {
Automaton::prefix_exact(automaton_index, 1, word)
};
automaton_index += 1;
original_automatons.push(automaton);
}
automatons.push(AutomatonGroup::normal(original_automatons));
for n in 1..=NGRAMS {
let mut ngrams = query_words.windows(n).enumerate().peekable();
while let Some((query_index, ngram_slice)) = ngrams.next() {
let query_range = query_index..query_index + n;
let ngram_nb_words = ngram_slice.len();
let ngram = ngram_slice.join(" ");
let has_following_word = ngrams.peek().is_some();
let not_prefix_dfa =
has_following_word || has_end_whitespace || ngram.chars().all(is_cjk);
// automaton of synonyms of the ngrams
let normalized = normalize_str(&ngram);
let lev = if not_prefix_dfa {
build_dfa(&normalized)
} else {
build_prefix_dfa(&normalized)
};
let mut stream = synonyms.search(&lev).into_stream();
while let Some(base) = stream.next() {
// only trigger alternatives when the last word has been typed
// i.e. "new " do not but "new yo" triggers alternatives to "new york"
let base = std::str::from_utf8(base).unwrap();
let base_nb_words = split_query_string(base).count();
if ngram_nb_words != base_nb_words {
continue;
}
if let Some(synonyms) = synonym_store.synonyms(reader, base.as_bytes())? {
let mut stream = synonyms.into_stream();
while let Some(synonyms) = stream.next() {
let synonyms = std::str::from_utf8(synonyms).unwrap();
let synonyms_words: Vec<_> = split_query_string(synonyms).collect();
let nb_synonym_words = synonyms_words.len();
let real_query_index = automaton_index;
enhancer_builder.declare(
query_range.clone(),
real_query_index,
&synonyms_words,
);
for synonym in synonyms_words {
let automaton = if nb_synonym_words == 1 {
Automaton::exact(automaton_index, n, synonym)
} else {
Automaton::non_exact(automaton_index, n, synonym)
};
automaton_index += 1;
automatons.push(AutomatonGroup::normal(vec![automaton]));
}
}
}
}
if n == 1 {
if let Some((left, right)) =
split_best_frequency(reader, &normalized, postings_lists_store)?
{
let a = Automaton::exact(automaton_index, 1, left);
enhancer_builder.declare(query_range.clone(), automaton_index, &[left]);
automaton_index += 1;
let b = Automaton::exact(automaton_index, 1, right);
enhancer_builder.declare(query_range.clone(), automaton_index, &[left]);
automaton_index += 1;
automatons.push(AutomatonGroup::phrase_query(vec![a, b]));
}
} else {
// automaton of concatenation of query words
let concat = ngram_slice.concat();
let normalized = normalize_str(&concat);
let real_query_index = automaton_index;
enhancer_builder.declare(query_range.clone(), real_query_index, &[&normalized]);
let automaton = Automaton::exact(automaton_index, n, &normalized);
automaton_index += 1;
automatons.push(AutomatonGroup::normal(vec![automaton]));
}
}
}
// order automatons, the most important first,
// we keep the original automatons at the front.
automatons[1..].sort_by_key(|group| {
let a = group.automatons.first().unwrap();
(
Reverse(a.is_exact),
a.ngram,
Reverse(group.automatons.len()),
)
});
Ok((automatons, enhancer_builder.build()))
}

255
meilisearch-core/src/bucket_sort.rs
View File

@ -1,5 +1,5 @@
use std::ops::Deref;
use std::fmt;
use std::{cmp, fmt};
use std::borrow::Cow;
use std::mem;
use std::ops::Range;
@ -8,43 +8,68 @@ use std::time::{Duration, Instant};
use compact_arena::{SmallArena, Idx32, mk_arena};
use fst::{IntoStreamer, Streamer};
use hashbrown::HashMap;
use levenshtein_automata::DFA;
use log::debug;
use meilisearch_tokenizer::{is_cjk, split_query_string};
use meilisearch_types::{DocIndex, Highlight};
use meilisearch_types::DocIndex;
use sdset::{Set, SetBuf};
use slice_group_by::{GroupBy, GroupByMut};
use crate::automaton::NGRAMS;
use crate::automaton::{QueryEnhancer, QueryEnhancerBuilder};
use crate::automaton::{build_dfa, build_prefix_dfa, build_exact_dfa};
use crate::automaton::{normalize_str, split_best_frequency};
use crate::automaton::normalize_str;
use crate::automaton::{QueryEnhancer, QueryEnhancerBuilder};
use crate::criterion::Criteria;
use crate::levenshtein::prefix_damerau_levenshtein;
use crate::distinct_map::{BufferedDistinctMap, DistinctMap};
use crate::raw_document::RawDocument;
use crate::{database::MainT, reordered_attrs::ReorderedAttrs};
use crate::{store, Document, DocumentId, MResult};
pub fn bucket_sort<'c>(
pub fn bucket_sort<'c, FI>(
reader: &heed::RoTxn<MainT>,
query: &str,
range: Range<usize>,
filter: Option<FI>,
criteria: Criteria<'c>,
main_store: store::Main,
postings_lists_store: store::PostingsLists,
documents_fields_counts_store: store::DocumentsFieldsCounts,
synonyms_store: store::Synonyms,
) -> MResult<Vec<Document>>
where
FI: Fn(DocumentId) -> bool,
{
// We delegate the filter work to the distinct query builder,
// specifying a distinct rule that has no effect.
if filter.is_some() {
let distinct = |_| None;
let distinct_size = 1;
return bucket_sort_with_distinct(
reader,
query,
range,
filter,
distinct,
distinct_size,
criteria,
main_store,
postings_lists_store,
documents_fields_counts_store,
synonyms_store,
);
}
let (automatons, query_enhancer) =
construct_automatons2(reader, query, main_store, postings_lists_store, synonyms_store)?;
construct_automatons(reader, query, main_store, postings_lists_store, synonyms_store)?;
debug!("{:?}", query_enhancer);
let before_postings_lists_fetching = Instant::now();
mk_arena!(arena);
let mut bare_matches = fetch_matches(reader, &automatons, &mut arena, main_store, postings_lists_store)?;
let mut bare_matches =
fetch_matches(reader, &automatons, &mut arena, main_store, postings_lists_store)?;
debug!("bare matches ({}) retrieved in {:.02?}",
bare_matches.len(),
before_postings_lists_fetching.elapsed(),
@ -69,9 +94,6 @@ pub fn bucket_sort<'c>(
before_raw_documents_building.elapsed(),
);
dbg!(mem::size_of::<BareMatch>());
dbg!(mem::size_of::<SimpleMatch>());
let mut groups = vec![raw_documents.as_mut_slice()];
'criteria: for criterion in criteria.as_ref() {
@ -103,31 +125,166 @@ pub fn bucket_sort<'c>(
}
let iter = raw_documents.into_iter().skip(range.start).take(range.len());
let iter = iter.map(|d| {
let highlights = d.raw_matches.iter().flat_map(|sm| {
let postings_list = &arena[sm.postings_list];
let input = postings_list.input();
let query = &automatons[sm.query_index as usize].query;
postings_list.iter().map(move |m| {
let covered_area = if query.len() > input.len() {
input.len()
} else {
prefix_damerau_levenshtein(query.as_bytes(), input).1
};
Highlight { attribute: m.attribute, char_index: m.char_index, char_length: covered_area as u16 }
})
}).collect();
Document {
id: d.id,
highlights,
#[cfg(test)] matches: Vec::new(),
}
});
let iter = iter.map(|rd| Document::from_raw(rd, &automatons, &arena));
Ok(iter.collect())
}
pub fn bucket_sort_with_distinct<'c, FI, FD>(
reader: &heed::RoTxn<MainT>,
query: &str,
range: Range<usize>,
filter: Option<FI>,
distinct: FD,
distinct_size: usize,
criteria: Criteria<'c>,
main_store: store::Main,
postings_lists_store: store::PostingsLists,
documents_fields_counts_store: store::DocumentsFieldsCounts,
synonyms_store: store::Synonyms,
) -> MResult<Vec<Document>>
where
FI: Fn(DocumentId) -> bool,
FD: Fn(DocumentId) -> Option<u64>,
{
let (automatons, query_enhancer) =
construct_automatons(reader, query, main_store, postings_lists_store, synonyms_store)?;
let before_postings_lists_fetching = Instant::now();
mk_arena!(arena);
let mut bare_matches = fetch_matches(reader, &automatons, &mut arena, main_store, postings_lists_store)?;
debug!("bare matches ({}) retrieved in {:.02?}",
bare_matches.len(),
before_postings_lists_fetching.elapsed(),
);
let before_raw_documents_presort = Instant::now();
bare_matches.sort_unstable_by_key(|sm| sm.document_id);
debug!("sort by documents ids took {:.02?}", before_raw_documents_presort.elapsed());
let before_raw_documents_building = Instant::now();
let mut prefiltered_documents = 0;
let mut raw_documents = Vec::new();
for raw_matches in bare_matches.linear_group_by_key_mut(|sm| sm.document_id) {
prefiltered_documents += 1;
if let Some(raw_document) = RawDocument::new(raw_matches, &automatons, &mut arena) {
raw_documents.push(raw_document);
}
}
debug!("creating {} (original {}) candidates documents took {:.02?}",
raw_documents.len(),
prefiltered_documents,
before_raw_documents_building.elapsed(),
);
let mut groups = vec![raw_documents.as_mut_slice()];
let mut key_cache = HashMap::new();
let mut filter_map = HashMap::new();
// these two variables informs on the current distinct map and
// on the raw offset of the start of the group where the
// range.start bound is located according to the distinct function
let mut distinct_map = DistinctMap::new(distinct_size);
let mut distinct_raw_offset = 0;
'criteria: for criterion in criteria.as_ref() {
let tmp_groups = mem::replace(&mut groups, Vec::new());
let mut buf_distinct = BufferedDistinctMap::new(&mut distinct_map);
let mut documents_seen = 0;
for mut group in tmp_groups {
// if this group does not overlap with the requested range,
// push it without sorting and splitting it
if documents_seen + group.len() < distinct_raw_offset {
documents_seen += group.len();
groups.push(group);
continue;
}
let before_criterion_preparation = Instant::now();
criterion.prepare(&mut group, &mut arena, &query_enhancer, &automatons);
debug!("{:?} preparation took {:.02?}", criterion.name(), before_criterion_preparation.elapsed());
let before_criterion_sort = Instant::now();
group.sort_unstable_by(|a, b| criterion.evaluate(a, b, &arena));
debug!("{:?} evaluation took {:.02?}", criterion.name(), before_criterion_sort.elapsed());
for group in group.binary_group_by_mut(|a, b| criterion.eq(a, b, &arena)) {
// we must compute the real distinguished len of this sub-group
for document in group.iter() {
let filter_accepted = match &filter {
Some(filter) => {
let entry = filter_map.entry(document.id);
*entry.or_insert_with(|| (filter)(document.id))
}
None => true,
};
if filter_accepted {
let entry = key_cache.entry(document.id);
let key = entry.or_insert_with(|| (distinct)(document.id).map(Rc::new));
match key.clone() {
Some(key) => buf_distinct.register(key),
None => buf_distinct.register_without_key(),
};
}
// the requested range end is reached: stop computing distinct
if buf_distinct.len() >= range.end {
break;
}
}
documents_seen += group.len();
groups.push(group);
// if this sub-group does not overlap with the requested range
// we must update the distinct map and its start index
if buf_distinct.len() < range.start {
buf_distinct.transfert_to_internal();
distinct_raw_offset = documents_seen;
}
// we have sort enough documents if the last document sorted is after
// the end of the requested range, we can continue to the next criterion
if buf_distinct.len() >= range.end {
continue 'criteria;
}
}
}
}
// once we classified the documents related to the current
// automatons we save that as the next valid result
let mut seen = BufferedDistinctMap::new(&mut distinct_map);
let mut documents = Vec::with_capacity(range.len());
for raw_document in raw_documents.into_iter().skip(distinct_raw_offset) {
let filter_accepted = match &filter {
Some(_) => filter_map.remove(&raw_document.id).unwrap(),
None => true,
};
if filter_accepted {
let key = key_cache.remove(&raw_document.id).unwrap();
let distinct_accepted = match key {
Some(key) => seen.register(key),
None => seen.register_without_key(),
};
if distinct_accepted && seen.len() > range.start {
documents.push(Document::from_raw(raw_document, &automatons, &arena));
if documents.len() == range.len() {
break;
}
}
}
}
Ok(documents)
}
pub struct BareMatch<'tag> {
pub document_id: DocumentId,
pub query_index: u16,
@ -257,7 +414,7 @@ fn fetch_matches<'txn, 'tag>(
postings_lists_store: store::PostingsLists,
) -> MResult<Vec<BareMatch<'tag>>>
{
let mut before_words_fst = Instant::now();
let before_words_fst = Instant::now();
let words = match main_store.words_fst(reader)? {
Some(words) => words,
None => return Ok(Vec::new()),
@ -273,7 +430,7 @@ fn fetch_matches<'txn, 'tag>(
for (query_index, automaton) in automatons.iter().enumerate() {
let before_dfa = Instant::now();
let dfa = automaton.dfa();
let QueryWordAutomaton { query, is_exact, is_prefix, phrase_query } = automaton;
let QueryWordAutomaton { query, is_exact, .. } = automaton;
dfa_time += before_dfa.elapsed();
let mut number_of_words = 0;
@ -381,7 +538,35 @@ impl QueryWordAutomaton {
}
}
fn construct_automatons2(
fn split_best_frequency<'a>(
reader: &heed::RoTxn<MainT>,
word: &'a str,
postings_lists_store: store::PostingsLists,
) -> MResult<Option<(&'a str, &'a str)>> {
let chars = word.char_indices().skip(1);
let mut best = None;
for (i, _) in chars {
let (left, right) = word.split_at(i);
let left_freq = postings_lists_store
.postings_list(reader, left.as_ref())?
.map_or(0, |i| i.len());
let right_freq = postings_lists_store
.postings_list(reader, right.as_ref())?
.map_or(0, |i| i.len());
let min_freq = cmp::min(left_freq, right_freq);
if min_freq != 0 && best.map_or(true, |(old, _, _)| min_freq > old) {
best = Some((min_freq, left, right));
}
}
Ok(best.map(|(_, l, r)| (l, r)))
}
fn construct_automatons(
reader: &heed::RoTxn<MainT>,
query: &str,
main_store: store::Main,

34
meilisearch-core/src/lib.rs
View File

@ -30,6 +30,10 @@ pub use self::store::Index;
pub use self::update::{EnqueuedUpdateResult, ProcessedUpdateResult, UpdateStatus, UpdateType};
pub use meilisearch_types::{DocIndex, DocumentId, Highlight, AttrCount};
use compact_arena::SmallArena;
use crate::bucket_sort::{QueryWordAutomaton, PostingsListView};
use crate::levenshtein::prefix_damerau_levenshtein;
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Document {
pub id: DocumentId,
@ -39,6 +43,36 @@ pub struct Document {
// pub matches: Vec<TmpMatch>,
}
impl Document {
pub fn from_raw<'a, 'tag, 'txn>(
raw_document: RawDocument<'a, 'tag>,
automatons: &[QueryWordAutomaton],
arena: &SmallArena<'tag, PostingsListView<'txn>>,
) -> Document
{
let highlights = raw_document.raw_matches.iter().flat_map(|sm| {
let postings_list = &arena[sm.postings_list];
let input = postings_list.input();
let query = &automatons[sm.query_index as usize].query;
postings_list.iter().map(move |m| {
let covered_area = if query.len() > input.len() {
input.len()
} else {
prefix_damerau_levenshtein(query.as_bytes(), input).1
};
Highlight {
attribute: m.attribute,
char_index: m.char_index,
char_length: covered_area as u16,
}
})
}).collect();
Document { id: raw_document.id, highlights }
}
}
#[cfg(test)]
mod tests {
use super::*;

18
meilisearch-core/src/query_builder.rs
View File

@ -1,7 +1,8 @@
use std::ops::Range;
use std::time::Duration;
use crate::{bucket_sort::bucket_sort, database::MainT};
use crate::database::MainT;
use crate::bucket_sort::{bucket_sort, bucket_sort_with_distinct};
use crate::{criterion::Criteria, Document, DocumentId};
use crate::{reordered_attrs::ReorderedAttrs, store, MResult};
@ -85,11 +86,24 @@ impl<'c, 'f, 'd> QueryBuilder<'c, 'f, 'd> {
range: Range<usize>,
) -> MResult<Vec<Document>> {
match self.distinct {
Some((distinct, distinct_size)) => unimplemented!("distinct"),
Some((distinct, distinct_size)) => bucket_sort_with_distinct(
reader,
query,
range,
self.filter,
distinct,
distinct_size,
self.criteria,
self.main_store,
self.postings_lists_store,
self.documents_fields_counts_store,
self.synonyms_store,
),
None => bucket_sort(
reader,
query,
range,
self.filter,
self.criteria,
self.main_store,
self.postings_lists_store,

2
meilisearch-core/src/raw_document.rs
View File

@ -44,7 +44,7 @@ impl<'a, 'tag> RawDocument<'a, 'tag> {
let pla = &postings_lists[a.postings_list];
let plb = &postings_lists[b.postings_list];
let mut iter = itertools::merge_join_by(pla.iter(), plb.iter(), |a, b| {
let iter = itertools::merge_join_by(pla.iter(), plb.iter(), |a, b| {
a.attribute.cmp(&b.attribute).then((a.word_index + 1).cmp(&b.word_index))
});