optimize UDF split
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Key: HIVE-664
URL: https://issues.apache.org/jira/browse/HIVE-664
Project: Hadoop Hive
Issue Type: Bug
Components: Query Processor
Reporter: Namit Jain
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.
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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
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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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