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From "Ankit Modi (JIRA)" <j...@apache.org>
Subject [jira] Assigned: (PIG-965) PERFORMANCE: optimize common case in matches (PORegex)
Date Tue, 17 Nov 2009 19:54:39 GMT

     [ https://issues.apache.org/jira/browse/PIG-965?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Ankit Modi reassigned PIG-965:
------------------------------

    Assignee: Ankit Modi

> 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
>
> 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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