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Date: Fri, 2 Apr 2010 19:34:27 +0000 (UTC)
From: "Sergey Vladimirov (JIRA)" <jira@apache.org>
To: java-dev@lucene.apache.org
Subject: [jira] Created: (LUCENE-2362) Add support for slow filters with
 batch processing
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Add support for slow filters with batch processing
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                 Key: LUCENE-2362
                 URL: https://issues.apache.org/jira/browse/LUCENE-2362
             Project: Lucene - Java
          Issue Type: Improvement
          Components: Search
    Affects Versions: 3.0.1
            Reporter: Sergey Vladimirov


Internal implementation of IndexSearch assumes that Filter and scorer has almost equal perfomance. But in our environment we have Filter implementation that is very expensive (in compare to scorer).

if we have, let's say, 2k of termdocs selected by scorer (each ~250 docs) and 2k selected by filter, then 250k docs will be fastly checked (and filtered out) by scorer, and 250k docs will be slowly checked by our filter.

Using straigthforward implementation makes search out of 60 seconds per query boundary, because each next() or advance() requires N queries to database PER CHECKED DOC. Using read ahead technique allows us to optimze it to 35 seconds per query. Still too slow.

The solution to problem is firstly select all documents by scorer and filter them in batch by our filter. Example of implementation (with BitSet) in attachement. Currently it takes only ~300 millseconds per query.

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