[jira] Commented: (HIVE-542) Faster String Like

["Zheng Shao (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-542?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12719728#action_12719728 ] 

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: https://issues.apache.org/jira/browse/HIVE-542
>             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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