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Posted to dev@lucene.apache.org by "Michael McCandless (JIRA)" <ji...@apache.org> on 2010/09/13 20:45:32 UTC
[jira] Updated: (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:all-tabpanel ]
Michael McCandless updated LUCENE-1536:
---------------------------------------
Attachment: CachedFilterIndexReader.java
By subclassing FilterIndexReader, and taking advantage of how the flex
APIs now let you pass a custom skipDocs when pulling the postings, I
created a prototype class (attached, named CachedFilterIndexReader) that
up-front compiles the deleted docs for each segment with the negation
of a Filter (that you provide), and returns a reader that applies that
filter.
This is nice because it's fully external to Lucene, and it gives
awesome gains in many cases (see
http://chbits.blogspot.com/2010/09/fast-search-filters-using-flex.html).
I don't think we should commit this class -- we should instead fix
Filters correctly! But it's a nice workaround until we do that.
> 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: 4.0
>
> Attachments: CachedFilterIndexReader.java, LUCENE-1536.patch, LUCENE-1536.patch, LUCENE-1536.patch, LUCENE-1536.patch, 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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