[LUCENE-6332] join query scanning "toField" docValue

• Type: New Feature
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 5.0
• Component/s: modules/join
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Mikhail Khludnev
• Created: 03/Mar/15 20:28
• Updated: 12/Mar/15 09:45

Description

I want to contribute the subj which should do something like ..WHERE EXISTS (SELECT 1 FROM fromSearcher.search(fromQuery) WHERE fromField=toField). It turns out, that it can be returned by the current method createJoinQuery(...ScoreMode.None)

• at first, it should run fromQuery first, collect fromField into BytesRefHash by TermsCollector, like it's done now
• then it should return query with TwoPhase Scorer
• which obtains toField docValue on matches() and check term for existence in BytesRefHash

Do you think it's ever useful? if you do, I can bake a patch.
Anyway, suggest the better API eg separate method, or enum and actual name!

Issue Links

• relates to: SOLR-6234 Scoring modes for query time join
• links to: SemiJoin reminder
• links to: spin off from the mail