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https://issues.apache.org/jira/browse/SOLR-13132?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17152953#comment-17152953
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Chris M. Hostetter commented on SOLR-13132:
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bq. I'll try to pull something together that encapsulates these variables in an
illustrative way: comparing with filterCache sufficient to hold all terms,
filterCache disabled, filterCache thrashing (probably worst-case, and most
realistic), and for different cardinality fields and DocSet domains.
Yeah .. we don't need to go crazy, but it would be nice to double check that as
the branch stands now:
* using sweep on a field whose cardinality is much greater then the filterCache
size *IS* _faster_ then master.
* using sweep on a field whose cardinality is smaller then the filterCache size
*IS NOT* _significantly slower_ then master.
** even if it is: that's not a deal breaker, we then just need to
*** check that in this case: disabling sweep *IS* _as fast_ as master
*** document the trade off of disabling sweep
Speaking of docs: i skimmed the state of the branch and the ref-guide edits
look out of date from some of the code changes? (mentions
{{disable_sweep_collection}} and {{cacheDf}}) ... can you please fix?
> Improve JSON "terms" facet performance when sorted by relatedness
> ------------------------------------------------------------------
>
> Key: SOLR-13132
> URL: https://issues.apache.org/jira/browse/SOLR-13132
> Project: Solr
> Issue Type: Improvement
> Components: Facet Module
> Affects Versions: 7.4, master (9.0)
> Reporter: Michael Gibney
> Priority: Major
> Attachments: SOLR-13132-with-cache-01.patch,
> SOLR-13132-with-cache.patch, SOLR-13132.patch, SOLR-13132_testSweep.patch
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> When sorting buckets by {{relatedness}}, JSON "terms" facet must calculate
> {{relatedness}} for every term.
> The current implementation uses a standard uninverted approach (either
> {{docValues}} or {{UnInvertedField}}) to get facet counts over the domain
> base docSet, and then uses that initial pass as a pre-filter for a
> second-pass, inverted approach of fetching docSets for each relevant term
> (i.e., {{count > minCount}}?) and calculating intersection size of those sets
> with the domain base docSet.
> Over high-cardinality fields, the overhead of per-term docSet creation and
> set intersection operations increases request latency to the point where
> relatedness sort may not be usable in practice (for my use case, even after
> applying the patch for SOLR-13108, for a field with ~220k unique terms per
> core, QTime for high-cardinality domain docSets were, e.g.: cardinality
> 1816684=9000ms, cardinality 5032902=18000ms).
> The attached patch brings the above example QTimes down to a manageable
> ~300ms and ~250ms respectively. The approach calculates uninverted facet
> counts over domain base, foreground, and background docSets in parallel in a
> single pass. This allows us to take advantage of the efficiencies built into
> the standard uninverted {{FacetFieldProcessorByArray[DV|UIF]}}), and avoids
> the per-term docSet creation and set intersection overhead.
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