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From "Martijn van Groningen (JIRA)" <>
Subject [jira] [Commented] (SOLR-2564) Integrating grouping module into Solr 4.0
Date Wed, 08 Jun 2011 11:12:58 GMT


Martijn van Groningen commented on SOLR-2564:

I've been checking out the performance, and it generally seems fine. But of course we normally
short circuit based on comparators and often don't get beyond that... so to exercise &
isolate the rest of the code, I tried a worst-case scenario where the short circuit wouldn't
work (sort=docid desc) and solr trunk with this patch is ~16% slower than without it. Any
ideas what the problem might be?

What might be the problem is that the trunk is using ( 589):
SearchGroup smallest = orderedGroups.pollLast();

Whilst the AbstractFirstPassGroupingCollector (line 217) is using:
final CollectedSearchGroup<GROUP_VALUE_TYPE> bottomGroup = orderedGroups.last();
The above also happen around line 271.

I haven't checked this out, but I think it is the most likely explanation between those two
implementations. Retrieving the bottom will be done in almost all cases when the short circuit
doesn't work 

> Integrating grouping module into Solr 4.0
> -----------------------------------------
>                 Key: SOLR-2564
>                 URL:
>             Project: Solr
>          Issue Type: Improvement
>            Reporter: Martijn van Groningen
>            Assignee: Martijn van Groningen
>             Fix For: 4.0
>         Attachments: LUCENE-2564.patch, SOLR-2564.patch, SOLR-2564.patch, SOLR-2564.patch,
SOLR-2564.patch, SOLR-2564.patch
> Since work on grouping module is going well. I think it is time to wire this up in Solr.
> Besides the current grouping features Solr provides, Solr will then also support second
pass caching and total count based on groups.

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