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From "Zheng Shao (JIRA)" <>
Subject [jira] Commented: (HIVE-542) Faster String Like
Date Mon, 15 Jun 2009 19:29:07 GMT


Zheng Shao commented on HIVE-542:

Since there are so many advanced string matching algorithms (e.g. KMP and its variants), we
should limit the scope here and maybe only optimize for the simplest case: "LIKE" that can
be replaced by something like String.find().

Basically, if the pattern is in the form of "%xxx%" where xxx does not contain any wildcards,
we can do "find".
If the pattern is in the form of "%xxx" or "xxx%", we can also do very efficient computation.

> Faster String Like
> ------------------
>                 Key: HIVE-542
>                 URL:
>             Project: Hadoop Hive
>          Issue Type: Improvement
>          Components: Query Processor
>    Affects Versions: 0.4.0
>            Reporter: Zheng Shao
> Currently Hive uses regular expression to do string like which is really really slow.
We should implement "LIKE" natively using Text.

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