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.
97 lines
2.6 KiB
Go
97 lines
2.6 KiB
Go
// Copyright (c) 2014 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 query
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import (
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"regexp"
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"strings"
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"github.com/blevesearch/bleve/index"
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"github.com/blevesearch/bleve/mapping"
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"github.com/blevesearch/bleve/search"
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"github.com/blevesearch/bleve/search/searcher"
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)
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type RegexpQuery struct {
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Regexp string `json:"regexp"`
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FieldVal string `json:"field,omitempty"`
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BoostVal *Boost `json:"boost,omitempty"`
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compiled *regexp.Regexp
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}
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// NewRegexpQuery creates a new Query which finds
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// documents containing terms that match the
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// specified regular expression. The regexp pattern
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// SHOULD NOT include ^ or $ modifiers, the search
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// will only match entire terms even without them.
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func NewRegexpQuery(regexp string) *RegexpQuery {
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return &RegexpQuery{
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Regexp: regexp,
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}
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}
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func (q *RegexpQuery) SetBoost(b float64) {
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boost := Boost(b)
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q.BoostVal = &boost
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}
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func (q *RegexpQuery) Boost() float64 {
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return q.BoostVal.Value()
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}
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func (q *RegexpQuery) SetField(f string) {
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q.FieldVal = f
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}
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func (q *RegexpQuery) Field() string {
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return q.FieldVal
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}
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func (q *RegexpQuery) Searcher(i index.IndexReader, m mapping.IndexMapping, options search.SearcherOptions) (search.Searcher, error) {
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field := q.FieldVal
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if q.FieldVal == "" {
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field = m.DefaultSearchField()
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}
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err := q.compile()
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if err != nil {
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return nil, err
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}
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return searcher.NewRegexpSearcher(i, q.compiled, field, q.BoostVal.Value(), options)
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}
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func (q *RegexpQuery) Validate() error {
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return q.compile()
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}
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func (q *RegexpQuery) compile() error {
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if q.compiled == nil {
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// require that pattern NOT be anchored to start and end of term
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actualRegexp := q.Regexp
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if strings.HasPrefix(actualRegexp, "^") {
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actualRegexp = actualRegexp[1:] // remove leading ^
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}
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// do not attempt to remove trailing $, it's presence is not
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// known to interfere with LiteralPrefix() the way ^ does
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// and removing $ introduces possible ambiguities with escaped \$, \\$, etc
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var err error
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q.compiled, err = regexp.Compile(actualRegexp)
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if err != nil {
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return err
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}
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}
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return nil
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}
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