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https://issues.apache.org/jira/browse/LUCENE-933?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12506342
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Doron Cohen commented on LUCENE-933:
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> a) +foo:BBB +()
> I have no idea what the "right" thing to do for situation (a) is.
Interestingly, see TestQueryParser.testQPA():
assertQueryEquals("term +stop term", qpAnalyzer, "term term");
assertQueryEquals("term -stop term", qpAnalyzer, "term term");
So today already requiring word W to not/appear become a non-requirement in
case W is a stopword.
Currently adding any of these would cause failure:
assertQueryEquals("term +(stop) term", qpAnalyzer, "term term");
assertQueryEquals("term -(stop) term", qpAnalyzer, "term term");
assertQueryEquals("term +(stop stop) term", qpAnalyzer, "term term");
assertQueryEquals("term -(stop stop) term", qpAnalyzer, "term term");
I feel comfortable with applying the logic we have for a single (stop)word on a
group of (stop)words, i.e. making the added lines pass.
Interestingly, consider this query:
A B +(+C -C)
Regularly it would have no match, because
X AND NOT X == FALSE
but if C is a stopword, with the fixed(?) logic the query would become:
A B
and might have matches.
Now is that a glitch? I'd like to think not.
> QueryParser can produce empty sub BooleanQueries when Analyzer proudces no
> tokens for input
> -------------------------------------------------------------------------------------------
>
> Key: LUCENE-933
> URL: https://issues.apache.org/jira/browse/LUCENE-933
> Project: Lucene - Java
> Issue Type: Bug
> Reporter: Hoss Man
>
> as triggered by SOLR-261, if you have a query like this...
> +foo:BBB +(yak:AAA baz:CCC)
> ...where the analyzer produces no tokens for the "yak:AAA" or "baz:CCC"
> portions of the query (posisbly because they are stop words) the resulting
> query produced by the QueryParser will be...
> +foo:BBB +()
> ...that is a BooleanQuery with two required clauses, one of which is an empty
> BooleanQuery with no clauses.
> this does not appear to be "good" behavior.
> In general, QueryParser should be smarter about what it does when parsing
> encountering parens whose contents result in an empty BooleanQuery -- but
> what exactly it should do in the following situations...
> a) +foo:BBB +()
> b) +foo:BBB ()
> c) +foo:BBB -()
> ...is up for interpretation. I would think situation (b) clearly lends
> itself to dropping the sub-BooleanQuery completely. situation (c) may also
> lend itself to that solution, since semanticly it means "don't allow a match
> on any queries in the empty set of queries". .... I have no idea what the
> "right" thing to do for situation (a) is.
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