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From "Mark Miller (JIRA)" <j...@apache.org>
Subject [jira] Updated: (LUCENE-502) TermScorer caches values unnecessarily
Date Thu, 13 Nov 2008 03:45:44 GMT

     [ https://issues.apache.org/jira/browse/LUCENE-502?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Mark Miller updated LUCENE-502:
-------------------------------

    Attachment: LUCENE-502.patch

> TermScorer caches values unnecessarily
> --------------------------------------
>
>                 Key: LUCENE-502
>                 URL: https://issues.apache.org/jira/browse/LUCENE-502
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>    Affects Versions: 1.9
>            Reporter: Steven Tamm
>            Priority: Minor
>         Attachments: LUCENE-502.patch, TermScorer.patch
>
>
> TermScorer aggressively caches the doc and freq of 32 documents at a time for each term
scored.  When querying for a lot of terms, this causes a lot of garbage to be created that's
unnecessary.  The SegmentTermDocs from which it retrieves its information doesn't have any
optimizations for bulk loading, and it's unnecessary.
> In addition, it has a SCORE_CACHE, that's of limited benefit.  It's caching the result
of a sqrt that should be placed in DefaultSimilarity, and if you're only scoring a few documents
that contain those terms, there's no need to precalculate the SQRT, especially on modern VMs.
> Enclosed is a patch that replaces TermScorer with a version that does not cache the docs
or feqs.  In the case of a lot of queries, that saves 196 bytes/term, the unnecessary disk
IO, and extra SQRTs which adds up.

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