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https://issues.apache.org/jira/browse/LUCENE-7254?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15257785#comment-15257785
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Robert Muir commented on LUCENE-7254:
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{quote}
+1 I don't like that this patch might create iterators over sparse FixedBitSet
instances. I am fine with doing that temporarily for queries that are likely to
match many docs (I see that you modified the ranges but not the point-in-set
queries for instance) but in the longer term I think we should improve points
so that we can know earlier how many docs are going to be added.
{quote}
No, it is the opposite way around. The sparse case is not the case to optimize
because it is already fast.
not doing point-in-set had nothing to do with that. I just don't have a good
benchmark for it. I think we should use the fastest bitset always here for
these queries.
Optimizations for esoteric/abuse/etc cases (many values in a structured field,
sparse fields) shouldnt drag down the hotspot of these searches for the common
case.
> DocIDSetBuilder is no good for points
> -------------------------------------
>
> Key: LUCENE-7254
> URL: https://issues.apache.org/jira/browse/LUCENE-7254
> Project: Lucene - Core
> Issue Type: Bug
> Reporter: Robert Muir
> Attachments: LUCENE-7254.patch, LUCENE-7254.patch
>
>
> For the postings lists, I think this approach works well in dense cases (e.g.
> whole DISI's are added, things are coming in order, etc).
> However in the points case, it holds back range performance significantly.
> There are a couple of problems here:
> * expensive cardinality computation (this is a 2% hit) when its totally
> unnecessary. we can use index statistics to help here.
> * lots of conditional stuff in add(). This includes growing checks / bitset
> switching checks and so on (which happens even if you are smart and call
> grow, but this stuff all adds up).
> I dont think we should try to create a magical shared API that is both
> efficient for postings lists of unstructured stuff and at the same time point
> collection for structured fields, instead we should just do things
> differently for points and iterate from there.
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