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Posted to dev@lucene.apache.org by "Dawid Weiss (Issue Comment Edited) (JIRA)" <ji...@apache.org> on 2012/04/12 15:53:19 UTC
[jira] [Issue Comment Edited] (LUCENE-3972) Improve
AllGroupsCollector implementations
[ https://issues.apache.org/jira/browse/LUCENE-3972?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13252427#comment-13252427 ]
Dawid Weiss edited comment on LUCENE-3972 at 4/12/12 1:52 PM:
--------------------------------------------------------------
This is curious indeed. One thing to check would be this: SentinelIntSet uses no key rehashing (rehash simply returns the key). This resulted in very poor performance for certain regular integer sets (my experience from implementing HPPC). So while rehashing may seem like an additional overhead, it actually boosts performance.
Martijn -- could you patch the trunk's SentinelIntSet#rehash with, for example, this (murmur hash3 tail):
{noformat}
public static int rehash(int k)
{
k ^= k >>> 16;
k *= 0x85ebca6b;
k ^= k >>> 13;
k *= 0xc2b2ae35;
k ^= k >>> 16;
return k;
}
{noformat}
and retry your test? Btw. I'm not saying it'll be faster :)
was (Author: dweiss):
This is curious indeed. One thing to check would be this: SentinelIntSet uses no key rehashing (rehash simply returns the key). This resulted in very poor performance for certain regular integer sets (my experience from implementing HPPC). So while rehashing may seem like an additional overhead, it actually boosts performance.
Martijn -- could you patch the trunk's SentinelIntSet#rehash with, for example, this (murmur hash3 tail):
{noformat}
public static int rehash(int k)
{
k ^= k >>> 16;
k *= 0x85ebca6b;
k ^= k >>> 13;
k *= 0xc2b2ae35;
k ^= k >>> 16;
return k;
}
{noformat}
> Improve AllGroupsCollector implementations
> ------------------------------------------
>
> Key: LUCENE-3972
> URL: https://issues.apache.org/jira/browse/LUCENE-3972
> Project: Lucene - Java
> Issue Type: Improvement
> Components: modules/grouping
> Reporter: Martijn van Groningen
> Attachments: LUCENE-3972.patch, LUCENE-3972.patch
>
>
> I think that the performance of TermAllGroupsCollectorm, DVAllGroupsCollector.BR and DVAllGroupsCollector.SortedBR can be improved by using BytesRefHash to store the groups instead of an ArrayList.
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