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https://issues.apache.org/jira/browse/HIVE-664?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13793399#comment-13793399
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Teddy Choi commented on HIVE-664:
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mapreduce_stack_trace_hadoop20.q passed on my computer. The test doesn't call
split(), so it is not related with this patch.
> optimize UDF split
> ------------------
>
> Key: HIVE-664
> URL: https://issues.apache.org/jira/browse/HIVE-664
> Project: Hive
> Issue Type: Bug
> Components: UDF
> Reporter: Namit Jain
> Assignee: Teddy Choi
> Labels: optimization
> Attachments: HIVE-664.1.patch.txt, HIVE-664.2.patch.txt,
> HIVE-664.3.patch.txt
>
>
> Min Zhou added a comment - 21/Jul/09 07:34 AM
> It's very useful for us .
> some comments:
> 1. Can you implement it directly with Text ? Avoiding string decoding and
> encoding would be faster. Of course that trick may lead to another problem,
> as String.split uses a regular expression for splitting.
> 2. getDisplayString() always return a string in lowercase.
> [ Show » ]
> Min Zhou added a comment - 21/Jul/09 07:34 AM It's very useful for us . some
> comments:
> 1. Can you implement it directly with Text ? Avoiding string decoding and
> encoding would be faster. Of course that trick may lead to another problem,
> as String.split uses a regular expression for splitting.
> 2. getDisplayString() always return a string in lowercase.
> [ Permlink | « Hide ]
> Namit Jain added a comment - 21/Jul/09 09:22 AM
> Committed. Thanks Emil
> [ Show » ]
> Namit Jain added a comment - 21/Jul/09 09:22 AM Committed. Thanks Emil
> [ Permlink | « Hide ]
> Emil Ibrishimov added a comment - 21/Jul/09 10:48 AM
> There are some easy (compromise) ways to optimize split:
> 1. Check if the regex argument actually contains some "regex specific
> characters" and if it doesn't, do a straightforward split without converting
> to strings.
> 2. Assume some default value for the second argument (for example -
> split(str) to be equivalent to split(str, ' ') and optimize for this value
> 3. Have two separate split functions - one that does regex and one that
> splits around plain text.
> I think that 1 is a good choice and can be done rather quickly.
> [ Show » ]
> Emil Ibrishimov added a comment - 21/Jul/09 10:48 AM There are some easy
> (compromise) ways to optimize split: 1. Check if the regex argument actually
> contains some "regex specific characters" and if it doesn't, do a
> straightforward split without converting to strings. 2. Assume some default
> value for the second argument (for example - split(str) to be equivalent to
> split(str, ' ') and optimize for this value 3. Have two separate split
> functions - one that does regex and one that splits around plain text. I
> think that 1 is a good choice and can be done rather quickly.
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