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From "Robert Muir (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 13:55:30 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1536?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13124109#comment-13124109
] 

Robert Muir commented on LUCENE-1536:
-------------------------------------

one bug is that FilteredQuery in the patch runs some heuristics *per segment* which determine
how the booleans get set that drive the BS1 versus B2 decision.

This means that some segments could get BS1, and others get BS2, meaning we will rank some
documents arbitrarily higher than others when they actually have the same underlying index
statistics... this is bad!

So I think at least the parameters to subscorer (topLevel/inOrder) must be consistently applied
to all segments from that Weight.

                
> 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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