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https://issues.apache.org/jira/browse/LUCENE-1536?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Uwe Schindler updated LUCENE-1536:
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    Attachment: LUCENE-1536.patch

Further investigations showed more problems:
- FilteredDocIdSet does never implement Bits, but it should if the wrapped 
filter implements Bits. This cannot be done as two different implementation 
would be needed. I have no idea how to solve this.

I uploaded a new patch that fixes the problems from before:
- CachingWrapperFilter now only set the flag for containsOnlyLiveDocs to true, 
if it was true before, too. If the orginal filter returned a DocIdSet without 
that flag, the cached filter cannot suddenly set it to true
- CachingWrapperFilter also copies the liveDocs when it copies to FixedBitSet 
(e.g. QueryWrapperFilter).
- The default for containsOnlyLiveDocs is true, as all current filters were 
always resepcting this (exept FieldCacheRangeFilter since the rewrite). All 
filters in Lucene use liveDocs, because this was a requirement in older Lucene 
versions!
- QueryWrapperFilter may ignore liveDocs and simply return false for the flag.

In general I would like it more to rip the deleted docs handling in 
CachingWrapperFilter, as it no longer needs to take care. CWF should simply 
return containsOnlyLiveDocs=false if the deleted docs need to be merged in. 
There is no need to and them in using FilteredDocIdSet (which slows down for 
the random access case, see above)
                
> 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, 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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