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From Mark Miller <markrmil...@gmail.com>
Subject Re: [jira] Commented: (LUCENE-1997) Explore performance of multi-PQ vs single-PQ sorting API
Date Mon, 02 Nov 2009 23:13:44 GMT
Also, eg is Latin for roughly "for example" - so it's not "the"  
concern ;)

- Mark

http://www.lucidimagination.com (mobile)

On Nov 2, 2009, at 6:04 PM, "Jake Mannix (JIRA)" <jira@apache.org>  
wrote:

>
>    [ https://issues.apache.org/jira/browse/LUCENE-1997?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12772741#action_12772741

>  ]
>
> Jake Mannix commented on LUCENE-1997:
> -------------------------------------
>
> The current concern is to do with the memory?  I'm more concerned  
> with the weird "java ghosts" that are flying around, sometimes  
> swaying results by 20-40%...  the memory could only be an issue on a  
> setup with hundreds of segments and sorting the top 1000 values (do  
> we really try to optimize for this performance case?).  In the  
> normal case (no more than tens of segments, and the top 10 or 100  
> hits), we're talking about what, 100-1000 PQ entries?
>
>> Explore performance of multi-PQ vs single-PQ sorting API
>> --------------------------------------------------------
>>
>>                Key: LUCENE-1997
>>                URL: https://issues.apache.org/jira/browse/LUCENE-1997
>>            Project: Lucene - Java
>>         Issue Type: Improvement
>>         Components: Search
>>   Affects Versions: 2.9
>>           Reporter: Michael McCandless
>>           Assignee: Michael McCandless
>>        Attachments: LUCENE-1997.patch, LUCENE-1997.patch,  
>> LUCENE-1997.patch, LUCENE-1997.patch, LUCENE-1997.patch,  
>> LUCENE-1997.patch, LUCENE-1997.patch, LUCENE-1997.patch,  
>> LUCENE-1997.patch
>>
>>
>> Spinoff from recent "lucene 2.9 sorting algorithm" thread on java- 
>> dev,
>> where a simpler (non-segment-based) comparator API is proposed that
>> gathers results into multiple PQs (one per segment) and then merges
>> them in the end.
>> I started from John's multi-PQ code and worked it into
>> contrib/benchmark so that we could run perf tests.  Then I generified
>> the Python script I use for running search benchmarks (in
>> contrib/benchmark/sortBench.py).
>> The script first creates indexes with 1M docs (based on
>> SortableSingleDocSource, and based on wikipedia, if available).  Then
>> it runs various combinations:
>>  * Index with 20 balanced segments vs index with the "normal" log
>>    segment size
>>  * Queries with different numbers of hits (only for wikipedia index)
>>  * Different top N
>>  * Different sorts (by title, for wikipedia, and by random string,
>>    random int, and country for the random index)
>> For each test, 7 search rounds are run and the best QPS is kept.  The
>> script runs singlePQ then multiPQ, and records the resulting best QPS
>> for each and produces table (in Jira format) as output.
>
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