b55c9043b9
While researching an observed performance issue with wildcard queries, it was observed that the LiteralPrefix() method on the regexp.Regexp struct did not always behave as expected. In particular, when the pattern starts with ^, AND involves some backtracking, the LiteralPrefix() seems to always be the empty string. The side-effect of this is that we rely on having a helpful prefix, to reduce the number of terms in the term dictionary that need to be visited. This change now makes the searcher enforce start/end on the term directly, by using FindStringIndex() instead of Match(). Next, we also modified WildcardQuery and RegexpQuery to no longer include the ^ and $ modifiers. Documentation was also udpated to instruct users that they should not include the ^ and $ modifiers in their patterns.
99 lines
3.0 KiB
Go
99 lines
3.0 KiB
Go
// Copyright (c) 2015 Couchbase, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package searcher
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import (
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"regexp"
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"github.com/blevesearch/bleve/index"
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"github.com/blevesearch/bleve/search"
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)
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// NewRegexpSearcher creates a searcher which will match documents that
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// contain terms which match the pattern regexp. The match must be EXACT
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// matching the entire term. The provided regexp SHOULD NOT start with ^
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// or end with $ as this can intefere with the implementation. Separately,
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// matches will be checked to ensure they match the entire term.
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func NewRegexpSearcher(indexReader index.IndexReader, pattern *regexp.Regexp, field string, boost float64, options search.SearcherOptions) (search.Searcher, error) {
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prefixTerm, complete := pattern.LiteralPrefix()
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var candidateTerms []string
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if complete {
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// there is no pattern
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candidateTerms = []string{prefixTerm}
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} else {
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var err error
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candidateTerms, err = findRegexpCandidateTerms(indexReader, pattern, field, prefixTerm)
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if err != nil {
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return nil, err
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}
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}
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// enumerate all the terms in the range
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qsearchers := make([]search.Searcher, 0, len(candidateTerms))
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qsearchersClose := func() {
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for _, searcher := range qsearchers {
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_ = searcher.Close()
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}
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}
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for _, cterm := range candidateTerms {
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qsearcher, err := NewTermSearcher(indexReader, cterm, field, boost, options)
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if err != nil {
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qsearchersClose()
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return nil, err
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}
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qsearchers = append(qsearchers, qsearcher)
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}
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// build disjunction searcher of these ranges
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searcher, err := NewDisjunctionSearcher(indexReader, qsearchers, 0, options)
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if err != nil {
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qsearchersClose()
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return nil, err
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}
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return searcher, err
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}
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func findRegexpCandidateTerms(indexReader index.IndexReader, pattern *regexp.Regexp, field, prefixTerm string) (rv []string, err error) {
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rv = make([]string, 0)
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var fieldDict index.FieldDict
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if len(prefixTerm) > 0 {
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fieldDict, err = indexReader.FieldDictPrefix(field, []byte(prefixTerm))
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} else {
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fieldDict, err = indexReader.FieldDict(field)
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}
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defer func() {
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if cerr := fieldDict.Close(); cerr != nil && err == nil {
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err = cerr
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}
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}()
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// enumerate the terms and check against regexp
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tfd, err := fieldDict.Next()
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for err == nil && tfd != nil {
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matchPos := pattern.FindStringIndex(tfd.Term)
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if matchPos != nil && matchPos[0] == 0 && matchPos[1] == len(tfd.Term) {
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rv = append(rv, tfd.Term)
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if tooManyClauses(len(rv)) {
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return rv, tooManyClausesErr()
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}
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}
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tfd, err = fieldDict.Next()
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}
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return rv, err
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}
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