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From "Teddy Choi (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-664) optimize UDF split
Date Sat, 12 Oct 2013 16:26:43 GMT

    [ https://issues.apache.org/jira/browse/HIVE-664?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13793399#comment-13793399
] 

Teddy Choi commented on HIVE-664:
---------------------------------

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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