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https://issues.apache.org/jira/browse/LUCENE-7337?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael McCandless updated LUCENE-7337:
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Attachment: LUCENE-7337.patch
OK, here's a patch, giving {{MatchNoDocsQuery}} its own {{Weight}}
that returns 0 for {{queryNorm}}, and fixing an empty {{BooleanQuery}}
to rewrite to it.
Scoring wise, this behaves the same as an empty-clause boolean query,
and I think this will make LUCENE-7276 much easier!
bq. It can also happen when multiple indices are requested (Solr/ElasticSearch
case).
I think getting proper distributed queries working is really out of
scope here: that would really require a distributed rewrite to work
correctly.
I think this patch is a good baby-step.
> MultiTermQuery are sometimes rewritten into an empty boolean query
> ------------------------------------------------------------------
>
> Key: LUCENE-7337
> URL: https://issues.apache.org/jira/browse/LUCENE-7337
> Project: Lucene - Core
> Issue Type: Bug
> Components: core/search
> Reporter: Ferenczi Jim
> Priority: Minor
> Attachments: LUCENE-7337.patch
>
>
> MultiTermQuery are sometimes rewritten to an empty boolean query (depending
> on the rewrite method), it can happen when no expansions are found on a fuzzy
> query for instance.
> It can be problematic when the multi term query is boosted.
> For instance consider the following query:
> `((title:bar~1)^100 text:bar)`
> This is a boolean query with two optional clauses. The first one is a fuzzy
> query on the field title with a boost of 100.
> If there is no expansion for "title:bar~1" the query is rewritten into:
> `(()^100 text:bar)`
> ... and when expansions are found:
> `((title:bars | title:bar)^100 text:bar)`
> The scoring of those two queries will differ because the normalization factor
> and the norm for the first query will be equal to 1 (the boost is ignored
> because the empty boolean query is not taken into account for the computation
> of the normalization factor) whereas the second query will have a
> normalization factor of 10,000 (100*100) and a norm equal to 0.01.
> This kind of discrepancy can happen in a single index because the expansions
> for the fuzzy query are done at the segment level. It can also happen when
> multiple indices are requested (Solr/ElasticSearch case).
> A simple fix would be to replace the empty boolean query produced by the
> multi term query with a MatchNoDocsQuery but I am not sure that it's the best
> way to fix. WDYT ?
>
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