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