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https://issues.apache.org/jira/browse/SOLR-12243?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16836448#comment-16836448
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Michael Gibney commented on SOLR-12243:
---------------------------------------
[~fmr], there are several issues relevant to the problem you've encountered:
Multi-term synonyms invoke graphPhraseQuery, implemented for {{6.5 <= _version_
< 7.6}} as SpanNearQuery, which was not prone to exponential growth; but (also
prior to 7.6) that SpanNearQuery was completely ignored. It's the latter
problem (ignoring) that this issue (SOLR-12243) fixes.
The exponential expansion is related to LUCENE-8531, which reverts LUCENE-7699
by changing the SpanNearQuery graph phrase query implementation back to the
pre-6.5 MultiPhraseQuery implementation (when slop>0), for semantic
compatibility reasons.
MultiPhraseQuery is inherently susceptible to exponential expansion, so there
is no workaround at the moment to fully support a high degree of synonym
expansion in conjunction with slop>0. Regarding the manifestation of the
problem as "single query taking down an entire solr-server", this should be
mitigated starting in 8.1 (see SOLR-13336). Individual queries will still fail
if expanded beyond a configurable threshold (number of clauses), but the type
of systemic problem that you encountered will be prevented.
Regarding a potential longer-term solution, it might be worth looking at
LUCENE-8544.
> Edismax missing phrase queries when phrases contain multiterm synonyms
> ----------------------------------------------------------------------
>
> Key: SOLR-12243
> URL: https://issues.apache.org/jira/browse/SOLR-12243
> Project: Solr
> Issue Type: Bug
> Security Level: Public(Default Security Level. Issues are Public)
> Components: query parsers
> Affects Versions: 7.1
> Environment: RHEL, MacOS X
> Do not believe this is environment-specific.
> Reporter: Elizabeth Haubert
> Assignee: Steve Rowe
> Priority: Major
> Fix For: 7.6, 8.0
>
> Attachments: SOLR-12243.patch, SOLR-12243.patch, SOLR-12243.patch,
> SOLR-12243.patch, SOLR-12243.patch, SOLR-12243.patch, SOLR-12243.patch,
> multiword-synonyms.txt, schema.xml, solrconfig.xml
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> synonyms.txt:
> {code}
> allergic, hypersensitive
> aspirin, acetylsalicylic acid
> dog, canine, canis familiris, k 9
> rat, rattus
> {code}
> request handler:
> {code:xml}
> <requestHandler name="/test_qparse_error" class="solr.SearchHandler">
> <lst name="defaults">
> <!-- Query settings -->
> <str name="defType">edismax</str>
> <str name="tie"> 0.4</str>
> <str name="qf">title^100</str>
> <str name="pf">title~20^5000</str>
> <str name="pf2">title~11</str>
> <str name="pf3">title~22^1000</str>
> <str name="df">text</str>
> <!-- mm If two or fewer clauses exist, they all must match.
> If three to five clauses exist, one can be missing. If six to eight clauses
> exist, all but three must match.
> If more than nine clauses exist, only require 30% to match.-->
> <str name="mm">3<-1 6<-3 9<30%</str>
> <str name="q.alt">*:*</str>
> <str name="rows">25</str>
> </lst>
> </requestHandler>
> {code}
> Phrase queries (pf, pf2, pf3) containing "dog" or "aspirin" against the
> above list will not be generated.
> "allergic reaction dog" will generate pf2: "allergic reaction", but not
> pf:"allergic reaction dog", pf2: "reaction dog", or pf3: "allergic reaction
> dog"
> "aspirin dose in rats" will generate pf3: "dose ? rats" but not pf2: "aspirin
> dose" or pf3:"aspirin dose ?"
>
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