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https://issues.apache.org/jira/browse/LUCENE-1536?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13116702#comment-13116702
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Robert Muir commented on LUCENE-1536:
-------------------------------------
{quote}
Then separately we can figure out how a Filter/DIS/Bits conveys the "strategy"
to IS. Really this is a part of the wider question of how Lucene should do
query optimization in general...
{quote}
I think once we do this, we should just add "Bits acceptDocs" parameter to
IndexSearcher's searchWithFilter method?
And I think a simple (protected) heuristic to IndexSearcher whether it should
execute the filter 'via acceptDocs': the default just be instanceof Bits &&
firstSetBit < X, like what BQ does?
Then we might add optional boolean method to Filter for whether it already
'incorporates deletes'.
Then we can optimize for the 4 cases:
# sparse/non-random-access filter, doesn't incorporate deletes: same logic as
today
# sparse/non-random-access filter, incorporates deletes: Here we might pass
null as 'acceptDocs' to the scorercontext, so we no longer redundantly check
deleted docs.
# heavy random-access filter, doesn't incorporate deletes: no filter instead
with acceptDocs=AndBits(filter, liveDocs)
# heavy random-access filter, incorporates deletes: no filter instead with
acceptDocs=filter (don't need to use AndBits since we know it incorporates
liveDocs).
> 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: core/search
> Affects Versions: 2.4
> Reporter: Michael McCandless
> Assignee: Michael McCandless
> Priority: Minor
> Labels: gsoc2011, lucene-gsoc-11, mentor
> Fix For: 4.0
>
> Attachments: CachedFilterIndexReader.java, LUCENE-1536.patch,
> LUCENE-1536.patch, LUCENE-1536.patch, LUCENE-1536.patch, LUCENE-1536.patch,
> LUCENE-1536.patch, LUCENE-1536.patch, 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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