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Posted to dev@lucene.apache.org by "Uwe Schindler (JIRA)" <ji...@apache.org> on 2009/04/16 09:19:14 UTC
[jira] Commented: (LUCENE-1536) if a filter can support random
access API, we should use it
[ https://issues.apache.org/jira/browse/LUCENE-1536?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12699558#action_12699558 ]
Uwe Schindler commented on LUCENE-1536:
---------------------------------------
How about DocIdSet adds a
{code}
boolean isRandomAccess() { return false; }
{code}
That is implemented to return false in the default abstract class for backwards compatibility.
If a DocIdSet is random access (backed by OpenBitSet or is the empty iterator), isRandomAccess() is overridden to return true and an additional method in DocIdSet is implemented, the default would be:
{code}
boolean acceptDoc(int docid) { throw new UnsupportedOperationException(); }
{code}
Both changes are backwards compatible, but filters using OpenBitSet would automatically be random access and support acceptDoc().
> if a filter can support random access API, we should use it
> -----------------------------------------------------------
>
> Key: LUCENE-1536
> URL: https://issues.apache.org/jira/browse/LUCENE-1536
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Search
> Affects Versions: 2.4
> Reporter: Michael McCandless
> Assignee: Michael McCandless
> Priority: Minor
> Fix For: 2.9
>
> Attachments: LUCENE-1536.patch
>
>
> I ran some performance tests, comparing applying a filter via
> random-access API instead of current trunk's iterator API.
> This was inspired by LUCENE-1476, where we realized deletions should
> really be implemented just like a filter, but then in testing found
> that switching deletions to iterator was a very sizable performance
> hit.
> Some notes on the test:
> * Index is first 2M docs of Wikipedia. Test machine is Mac OS X
> 10.5.6, quad core Intel CPU, 6 GB RAM, java 1.6.0_07-b06-153.
> * I test across multiple queries. 1-X means an OR query, eg 1-4
> means 1 OR 2 OR 3 OR 4, whereas +1-4 is an AND query, ie 1 AND 2
> AND 3 AND 4. "u s" means "united states" (phrase search).
> * I test with multiple filter densities (0, 1, 2, 5, 10, 25, 75, 90,
> 95, 98, 99, 99.99999 (filter is non-null but all bits are set),
> 100 (filter=null, control)).
> * Method high means I use random-access filter API in
> IndexSearcher's main loop. Method low means I use random-access
> filter API down in SegmentTermDocs (just like deleted docs
> today).
> * Baseline (QPS) is current trunk, where filter is applied as iterator up
> "high" (ie in IndexSearcher's search loop).
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