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From "Uwe Schindler (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-1536) if a filter can support random access API, we should use it
Date Mon, 10 Oct 2011 04:44:30 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1536?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13123889#comment-13123889
] 

Uwe Schindler commented on LUCENE-1536:
---------------------------------------

bq. Hmm, with the latest patch have we lost the RECACHE option for CachingWrapperFilter? Ie,
to re-AND the filter bits with the latest live docs and cache that. This is useful if you
only periodically reopen the reader (and it has new deletes), so you don't have to AND the
deletes in for every query.

Mike: We can no longer do this, as the acceptDocs passed to the getDocIdSet() are no longer
always liveDocs, they can be everything. Simple example is two chained FilteredQuery. At least
you would need to add the liveDocs instance as key to the cache.

Even without recache we are still faster than before for a query, as the liveDocs are now
only applied once! Before they were not applied in the filter, but everywhere else in the
query. Now they are applied *once* per query. Putting them into the cache is stupid and wrong
and would only save us one AND. The complexity in CachingWrapperFilter does not rectify this.

About splitting that in two patches: I have no time to do it, I am on a business trip this
week.
                
> 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-rewrite.patch, LUCENE-1536-rewrite.patch,
LUCENE-1536-rewrite.patch, LUCENE-1536-rewrite.patch, LUCENE-1536-rewrite.patch, LUCENE-1536-rewrite.patch,
LUCENE-1536-rewrite.patch, LUCENE-1536-rewrite.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, LUCENE-1536.patch, LUCENE-1536.patch, LUCENE-1536.patch, LUCENE-1536.patch,
LUCENE-1536.patch, LUCENE-1536.patch, LUCENE-1536.patch, LUCENE-1536.patch, changes-yonik-uwe.patch,
luceneutil.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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