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Date: Wed, 16 Dec 2009 23:51:18 +0000 (UTC)
From: "Olga Natkovich (JIRA)" <jira@apache.org>
To: pig-dev@hadoop.apache.org
Subject: [jira] Updated: (PIG-965) PERFORMANCE: optimize common case in
 matches (PORegex)
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     [ https://issues.apache.org/jira/browse/PIG-965?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Olga Natkovich updated PIG-965:
-------------------------------

    Resolution: Fixed
        Status: Resolved  (was: Patch Available)

patch committed. Thanks Ankit for contributing and Thejas for reviewing!

> PERFORMANCE: optimize common case in matches (PORegex)
> ------------------------------------------------------
>
>                 Key: PIG-965
>                 URL: https://issues.apache.org/jira/browse/PIG-965
>             Project: Pig
>          Issue Type: Improvement
>          Components: impl
>            Reporter: Thejas M Nair
>            Assignee: Ankit Modi
>         Attachments: automaton.jar, poregex2.patch
>
>
> Some frequently seen use cases of 'matches' comparison operator have follow properties -
> 1. The rhs is a constant string . eg "c1 matches 'abc%' "
> 2. Regexes such that look for matching prefix , suffix etc are very common. eg - "abc%', "%abc", '%abc%' 
> To optimize for these common cases , PORegex.java can be changed to -
> 1. Compile the pattern (rhs of matches) re-use it if the pattern string has not changed. 
> 2. Use string comparisons for simple common regexes (in 2 above).
> The implementation of Hive like clause uses similar optimizations.

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