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https://issues.apache.org/jira/browse/SOLR-8988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15241993#comment-15241993
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Hoss Man commented on SOLR-8988:
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bq. As far as I can tell there is no reason to set facet.mincount=0 for
refinement purposes . After trying to make sense of all the refinement logic, I
cant see how the difference between no value and value=0 would have a negative
i haven't looked closely, but IIRC the justification for this comment...
{noformat}
- dff.initialMincount = 0; // TODO: we could change this to 1, but
would
- // then need more refinement for small facet
- // result sets?
{noformat}
is that if you get back a count of foo=0 from shardA, and if foo winds up being
a candidate term for the final topN list because of it's count on other shards,
then you know definitively that you don't have to ask shardA to provide a
refinement value for "foo" - you already know it's count.
which behavior is more performant in the most common cases? ... i have no idea
off the top of my head ... i'd have ot really sit down and think about all the
variables.
what would probably make the most sense is to add an expert level option for
controlling this (similar to the overrequest options) and leave the default as
it is for now -- that way people have one more knob they can try turning to
tune performance, and if we decide later that the default behavior should be
changed in the common case, it's easy to do.
> Improve facet.method=fcs performance in SolrCloud
> -------------------------------------------------
>
> Key: SOLR-8988
> URL: https://issues.apache.org/jira/browse/SOLR-8988
> Project: Solr
> Issue Type: Improvement
> Reporter: Keith Laban
> Attachments: SOLR-8988.patch
>
>
> This relates to SOLR-8559 -- which improves the algorithm used by fcs
> faceting when {{facet.mincount=1}}
> This patch allows {{facet.mincount}} to be sent as 1 for distributed queries.
> As far as I can tell there is no reason to set {{facet.mincount=0}} for
> refinement purposes . After trying to make sense of all the refinement logic,
> I cant see how the difference between _no value_ and _value=0_ would have a
> negative effect.
> *Test perf:*
> - ~15million unique terms
> - query matches ~3million documents
> *Params:*
> {code}
> facet.mincount=1
> facet.limit=500
> facet.method=fcs
> facet.sort=count
> {code}
> *Average Time Per Request:*
> - Before patch: ~20seconds
> - After patch: <1 second
> *Note*: all tests pass and in my test, the output was identical before and
> after patch.
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