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https://issues.apache.org/jira/browse/CASSANDRA-12915?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15763743#comment-15763743
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Alex Petrov commented on CASSANDRA-12915:
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We've had a short chat on IRC and it was agreed that we'll proceed with the fix
for the empty iterator for now. I've suggested several possible alternatives
that would help to improve the performance for the use-case right now.
[~iksaif] would you like to work on a patch for the empty iterator / empty
index result or should I do that? Thank you!
> SASI: Index intersection can be very inefficient
> ------------------------------------------------
>
> Key: CASSANDRA-12915
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12915
> Project: Cassandra
> Issue Type: Improvement
> Components: sasi
> Reporter: Corentin Chary
> Fix For: 3.x
>
>
> It looks like RangeIntersectionIterator.java and be pretty inefficient in
> some cases. Let's take the following query:
> SELECT data FROM table WHERE index1 = 'foo' AND index2 = 'bar';
> In this case:
> * index1 = 'foo' will match 2 items
> * index2 = 'bar' will match ~300k items
> On my setup, the query will take ~1 sec, most of the time being spent in
> disk.TokenTree.getTokenAt().
> if I patch RangeIntersectionIterator so that it doesn't try to do the
> intersection (and effectively only use 'index1') the query will run in a few
> tenth of milliseconds.
> I see multiple solutions for that:
> * Add a static thresold to avoid the use of the index for the intersection
> when we know it will be slow. Probably when the range size factor is very
> small and the range size is big.
> * CASSANDRA-10765
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