use std::borrow::Cow; use std::collections::HashMap; use std::hash::{Hash, Hasher}; use std::ops::Range; use std::time::Instant; use std::{cmp, fmt, iter::once}; use fst::{IntoStreamer, Streamer}; use itertools::{EitherOrBoth, merge_join_by}; use meilisearch_tokenizer::split_query_string; use sdset::{Set, SetBuf, SetOperation}; use slice_group_by::StrGroupBy; use crate::database::MainT; use crate::{store, DocumentId, DocIndex, MResult}; use crate::automaton::{build_dfa, build_prefix_dfa, build_exact_dfa}; use crate::QueryWordsMapper; #[derive(Clone, PartialEq, Eq, Hash)] pub enum Operation { And(Vec), Or(Vec), Query(Query), } impl fmt::Debug for Operation { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fn pprint_tree(f: &mut fmt::Formatter<'_>, op: &Operation, depth: usize) -> fmt::Result { match op { Operation::And(children) => { writeln!(f, "{:1$}AND", "", depth * 2)?; children.iter().try_for_each(|c| pprint_tree(f, c, depth + 1)) }, Operation::Or(children) => { writeln!(f, "{:1$}OR", "", depth * 2)?; children.iter().try_for_each(|c| pprint_tree(f, c, depth + 1)) }, Operation::Query(query) => writeln!(f, "{:2$}{:?}", "", query, depth * 2), } } pprint_tree(f, self, 0) } } impl Operation { fn tolerant(id: QueryId, prefix: bool, s: &str) -> Operation { Operation::Query(Query { id, prefix, kind: QueryKind::Tolerant(s.to_string()) }) } fn exact(id: QueryId, prefix: bool, s: &str) -> Operation { Operation::Query(Query { id, prefix, kind: QueryKind::Exact(s.to_string()) }) } fn phrase2(id: QueryId, prefix: bool, (left, right): (&str, &str)) -> Operation { Operation::Query(Query { id, prefix, kind: QueryKind::Phrase(vec![left.to_owned(), right.to_owned()]) }) } } pub type QueryId = usize; #[derive(Clone, Eq)] pub struct Query { pub id: QueryId, pub prefix: bool, pub kind: QueryKind, } impl PartialEq for Query { fn eq(&self, other: &Self) -> bool { self.prefix == other.prefix && self.kind == other.kind } } impl Hash for Query { fn hash(&self, state: &mut H) { self.prefix.hash(state); self.kind.hash(state); } } #[derive(Clone, PartialEq, Eq, Hash)] pub enum QueryKind { Tolerant(String), Exact(String), Phrase(Vec), } impl fmt::Debug for Query { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let Query { id, prefix, kind } = self; let prefix = if *prefix { String::from("Prefix") } else { String::default() }; match kind { QueryKind::Exact(word) => { f.debug_struct(&(prefix + "Exact")).field("id", &id).field("word", &word).finish() }, QueryKind::Tolerant(word) => { f.debug_struct(&(prefix + "Tolerant")).field("id", &id).field("word", &word).finish() }, QueryKind::Phrase(words) => { f.debug_struct(&(prefix + "Phrase")).field("id", &id).field("words", &words).finish() }, } } } #[derive(Debug, Default)] pub struct PostingsList { docids: SetBuf, matches: SetBuf, } pub struct Context { pub words_set: fst::Set, pub synonyms: store::Synonyms, pub postings_lists: store::PostingsLists, pub prefix_postings_lists: store::PrefixPostingsListsCache, } fn split_best_frequency<'a>(reader: &heed::RoTxn, ctx: &Context, word: &'a str) -> MResult> { 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 = ctx.postings_lists .postings_list(reader, left.as_bytes())? .map(|p| p.docids.len()) .unwrap_or(0); let right_freq = ctx.postings_lists .postings_list(reader, right.as_bytes())? .map(|p| p.docids.len()) .unwrap_or(0); 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 fetch_synonyms(reader: &heed::RoTxn, ctx: &Context, words: &[&str]) -> MResult>> { let words = words.join(" "); let set = ctx.synonyms.synonyms(reader, words.as_bytes())?.unwrap_or_default(); let mut strings = Vec::new(); let mut stream = set.stream(); while let Some(input) = stream.next() { if let Ok(input) = std::str::from_utf8(input) { let alts = input.split_ascii_whitespace().map(ToOwned::to_owned).collect(); strings.push(alts); } } Ok(strings) } fn is_last(iter: I) -> impl Iterator { let mut iter = iter.into_iter().peekable(); core::iter::from_fn(move || { iter.next().map(|item| (iter.peek().is_none(), item)) }) } fn create_operation(iter: I, f: F) -> Operation where I: IntoIterator, F: Fn(Vec) -> Operation, { let mut iter = iter.into_iter(); match (iter.next(), iter.next()) { (Some(first), None) => first, (first, second) => f(first.into_iter().chain(second).chain(iter).collect()), } } const MAX_NGRAM: usize = 3; pub fn create_query_tree( reader: &heed::RoTxn, ctx: &Context, query: &str, ) -> MResult<(Operation, HashMap>)> { let words = split_query_string(query).map(str::to_lowercase); let words: Vec<_> = words.filter(|s| !s.contains(char::is_whitespace)).enumerate().collect(); let mut mapper = QueryWordsMapper::new(words.iter().map(|(_, w)| w)); let mut ngrams = Vec::new(); for ngram in 1..=MAX_NGRAM { let ngiter = words.windows(ngram).enumerate().map(|(i, group)| { let before = words[0..i].windows(1).enumerate().map(|(i, g)| (i..i+1, g)); let after = words[i + ngram..].windows(1) .enumerate() .map(move |(j, g)| (i + j + ngram..i + j + ngram + 1, g)); before.chain(Some((i..i + ngram, group))).chain(after) }); for group in ngiter { let mut ops = Vec::new(); for (is_last, (range, words)) in is_last(group) { let mut alts = Vec::new(); match words { [(id, word)] => { let mut idgen = ((id + 1) * 100)..; let phrase = split_best_frequency(reader, ctx, word)? .map(|ws| { let id = idgen.next().unwrap(); idgen.next().unwrap(); mapper.declare(range.clone(), id, &[ws.0, ws.1]); Operation::phrase2(id, is_last, ws) }); let synonyms = fetch_synonyms(reader, ctx, &[word])? .into_iter() .map(|alts| { let id = idgen.next().unwrap(); mapper.declare(range.clone(), id, &alts); let mut idgen = once(id).chain(&mut idgen); let iter = alts.into_iter().map(|w| { let id = idgen.next().unwrap(); Operation::exact(id, false, &w) }); create_operation(iter, Operation::And) }); let query = Operation::tolerant(*id, is_last, word); alts.push(query); alts.extend(synonyms.chain(phrase)); }, words => { let id = words[0].0; let mut idgen = ((id + 1) * 100_usize.pow(ngram as u32))..; let words: Vec<_> = words.iter().map(|(_, s)| s.as_str()).collect(); for synonym in fetch_synonyms(reader, ctx, &words)? { let id = idgen.next().unwrap(); mapper.declare(range.clone(), id, &synonym); let mut idgen = once(id).chain(&mut idgen); let synonym = synonym.into_iter().map(|s| { let id = idgen.next().unwrap(); Operation::exact(id, false, &s) }); alts.push(create_operation(synonym, Operation::And)); } let id = idgen.next().unwrap(); let concat = words.concat(); alts.push(Operation::exact(id, is_last, &concat)); mapper.declare(range.clone(), id, &[concat]); } } ops.push(create_operation(alts, Operation::Or)); } ngrams.push(create_operation(ops, Operation::And)); if ngram == 1 { break } } } let operation = create_operation(ngrams, Operation::Or); let mapping = mapper.mapping(); Ok((operation, mapping)) } #[derive(Debug, Clone, PartialEq, Eq, Hash)] pub struct PostingsKey<'o> { pub query: &'o Query, pub input: Vec, pub distance: u8, pub is_exact: bool, } pub type Distance = u8; pub type Postings<'o, 'txn> = HashMap, Cow<'txn, Set>>; pub type Cache<'o, 'txn> = HashMap<&'o Operation, Cow<'txn, Set>>; pub struct QueryResult<'o, 'txn> { pub docids: Cow<'txn, Set>, pub queries: Postings<'o, 'txn>, } pub fn traverse_query_tree<'o, 'txn>( reader: &'txn heed::RoTxn, ctx: &Context, tree: &'o Operation, ) -> MResult> { fn execute_and<'o, 'txn>( reader: &'txn heed::RoTxn, ctx: &Context, cache: &mut Cache<'o, 'txn>, postings: &mut Postings<'o, 'txn>, depth: usize, operations: &'o [Operation], ) -> MResult>> { println!("{:1$}AND", "", depth * 2); let before = Instant::now(); let mut results = Vec::new(); for op in operations { if cache.get(op).is_none() { let docids = match op { Operation::And(ops) => execute_and(reader, ctx, cache, postings, depth + 1, &ops)?, Operation::Or(ops) => execute_or(reader, ctx, cache, postings, depth + 1, &ops)?, Operation::Query(query) => execute_query(reader, ctx, postings, depth + 1, &query)?, }; cache.insert(op, docids); } } for op in operations { if let Some(docids) = cache.get(op) { results.push(docids.as_ref()); } } let op = sdset::multi::Intersection::new(results); let docids = op.into_set_buf(); println!("{:3$}--- AND fetched {} documents in {:.02?}", "", docids.len(), before.elapsed(), depth * 2); Ok(Cow::Owned(docids)) } fn execute_or<'o, 'txn>( reader: &'txn heed::RoTxn, ctx: &Context, cache: &mut Cache<'o, 'txn>, postings: &mut Postings<'o, 'txn>, depth: usize, operations: &'o [Operation], ) -> MResult>> { println!("{:1$}OR", "", depth * 2); let before = Instant::now(); let mut results = Vec::new(); for op in operations { if cache.get(op).is_none() { let docids = match op { Operation::And(ops) => execute_and(reader, ctx, cache, postings, depth + 1, &ops)?, Operation::Or(ops) => execute_or(reader, ctx, cache, postings, depth + 1, &ops)?, Operation::Query(query) => execute_query(reader, ctx, postings, depth + 1, &query)?, }; cache.insert(op, docids); } } for op in operations { if let Some(docids) = cache.get(op) { results.push(docids.as_ref()); } } let op = sdset::multi::Union::new(results); let docids = op.into_set_buf(); println!("{:3$}--- OR fetched {} documents in {:.02?}", "", docids.len(), before.elapsed(), depth * 2); Ok(Cow::Owned(docids)) } fn execute_query<'o, 'txn>( reader: &'txn heed::RoTxn, ctx: &Context, postings: &mut Postings<'o, 'txn>, depth: usize, query: &'o Query, ) -> MResult>> { let before = Instant::now(); let Query { id, prefix, kind } = query; let docids: Cow> = match kind { QueryKind::Tolerant(word) => { if *prefix && word.len() <= 2 { let prefix = { let mut array = [0; 4]; let bytes = word.as_bytes(); array[..bytes.len()].copy_from_slice(bytes); array }; let mut docids = Vec::new(); // We retrieve the cached postings lists for all // the words that starts with this short prefix. let result = ctx.prefix_postings_lists.prefix_postings_list(reader, prefix)?.unwrap_or_default(); let key = PostingsKey { query, input: word.clone().into_bytes(), distance: 0, is_exact: false }; postings.insert(key, result.matches); docids.extend_from_slice(&result.docids); // We retrieve the exact postings list for the prefix, // because we must consider these matches as exact. if let Some(result) = ctx.postings_lists.postings_list(reader, word.as_bytes())? { let key = PostingsKey { query, input: word.clone().into_bytes(), distance: 0, is_exact: true }; postings.insert(key, result.matches); docids.extend_from_slice(&result.docids); } let before = Instant::now(); let docids = SetBuf::from_dirty(docids); println!("{:2$}prefix docids construction took {:.02?}", "", before.elapsed(), depth * 2); Cow::Owned(docids) } else { let dfa = if *prefix { build_prefix_dfa(word) } else { build_dfa(word) }; let byte = word.as_bytes()[0]; let mut stream = if byte == u8::max_value() { ctx.words_set.search(&dfa).ge(&[byte]).into_stream() } else { ctx.words_set.search(&dfa).ge(&[byte]).lt(&[byte + 1]).into_stream() }; let before = Instant::now(); let mut docids = Vec::new(); while let Some(input) = stream.next() { if let Some(result) = ctx.postings_lists.postings_list(reader, input)? { let distance = dfa.eval(input).to_u8(); let is_exact = *prefix == false && distance == 0 && input.len() == word.len(); docids.extend_from_slice(&result.docids); let key = PostingsKey { query, input: input.to_owned(), distance, is_exact }; postings.insert(key, result.matches); } } println!("{:3$}docids extend ({:?}) took {:.02?}", "", docids.len(), before.elapsed(), depth * 2); let before = Instant::now(); let docids = SetBuf::from_dirty(docids); println!("{:2$}docids construction took {:.02?}", "", before.elapsed(), depth * 2); Cow::Owned(docids) } }, QueryKind::Exact(word) => { // TODO support prefix and non-prefix exact DFA let dfa = build_exact_dfa(word); let byte = word.as_bytes()[0]; let mut stream = if byte == u8::max_value() { ctx.words_set.search(&dfa).ge(&[byte]).into_stream() } else { ctx.words_set.search(&dfa).ge(&[byte]).lt(&[byte + 1]).into_stream() }; let mut docids = Vec::new(); while let Some(input) = stream.next() { if let Some(result) = ctx.postings_lists.postings_list(reader, input)? { let distance = dfa.eval(input).to_u8(); docids.extend_from_slice(&result.docids); let key = PostingsKey { query, input: input.to_owned(), distance, is_exact: true }; postings.insert(key, result.matches); } } let before = Instant::now(); let docids = SetBuf::from_dirty(docids); println!("{:2$}docids construction took {:.02?}", "", before.elapsed(), depth * 2); Cow::Owned(docids) }, QueryKind::Phrase(words) => { // TODO support prefix and non-prefix exact DFA if let [first, second] = words.as_slice() { let first = ctx.postings_lists.postings_list(reader, first.as_bytes())?.unwrap_or_default(); let second = ctx.postings_lists.postings_list(reader, second.as_bytes())?.unwrap_or_default(); let iter = merge_join_by(first.matches.as_slice(), second.matches.as_slice(), |a, b| { let x = (a.document_id, a.attribute, (a.word_index as u32) + 1); let y = (b.document_id, b.attribute, b.word_index as u32); x.cmp(&y) }); let matches: Vec<_> = iter .filter_map(EitherOrBoth::both) .flat_map(|(a, b)| once(*a).chain(Some(*b))) .collect(); let before = Instant::now(); let mut docids: Vec<_> = matches.iter().map(|m| m.document_id).collect(); docids.dedup(); let docids = SetBuf::new(docids).unwrap(); println!("{:2$}docids construction took {:.02?}", "", before.elapsed(), depth * 2); let matches = Cow::Owned(SetBuf::new(matches).unwrap()); let key = PostingsKey { query, input: vec![], distance: 0, is_exact: true }; postings.insert(key, matches); Cow::Owned(docids) } else { println!("{:2$}{:?} skipped", "", words, depth * 2); Cow::default() } }, }; println!("{:4$}{:?} fetched {:?} documents in {:.02?}", "", query, docids.len(), before.elapsed(), depth * 2); Ok(docids) } let mut cache = Cache::new(); let mut postings = Postings::new(); let docids = match tree { Operation::And(ops) => execute_and(reader, ctx, &mut cache, &mut postings, 0, &ops)?, Operation::Or(ops) => execute_or(reader, ctx, &mut cache, &mut postings, 0, &ops)?, Operation::Query(query) => execute_query(reader, ctx, &mut postings, 0, &query)?, }; Ok(QueryResult { docids, queries: postings }) }