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Posted to issues@lucene.apache.org by "Adrien Grand (Jira)" <ji...@apache.org> on 2021/11/15 15:37:00 UTC
[jira] [Commented] (LUCENE-10233) Store docIds as bitset when leafCardinality = 1 to speed up addAll
[ https://issues.apache.org/jira/browse/LUCENE-10233?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17443902#comment-17443902 ]
Adrien Grand commented on LUCENE-10233:
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This is an interesting idea!
One drawback of this approach is that we're trying to keep the number of classes that implement oal.util.BitSet at 2, and this would be a 3rd one. I wonder if we could use SparseFixedBitSet instead of this new OffsetBitSet class?
> Store docIds as bitset when leafCardinality = 1 to speed up addAll
> ------------------------------------------------------------------
>
> Key: LUCENE-10233
> URL: https://issues.apache.org/jira/browse/LUCENE-10233
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/codecs
> Reporter: Feng Guo
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> In low cardinality points cases, id blocks will usually store doc ids that have the same point value, and {{intersect}} will get into {{addAll}} logic. If we store ids as bitset, and give the IntersectVisitor bulk visiting ability, we can speed up addAll because we can just execute the 'or' logic between the result and the block ids.
> Optimization will be triggered when the following conditions are met at the same time:
> # leafCardinality = 1
> # max(docId) - min(docId) <= 16 * pointCount (in order to avoid expanding too much storage)
> # no duplicate doc id
> I mocked a field that has 10,000,000 docs per value and search it with a 1 term PointInSetQuery, the build scorer time decreased from 71ms to 8ms.
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