[HIVE-664] optimize UDF split

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.3.0
• Component/s: UDF
• Labels: optimization
• Assignee: Teddy Choi
• Reporter: Namit Jain
• Created: 21/Jul/09 17:55
• Updated: 21/Jul/17 18:46
• Resolved: 06/Feb/17 04:54

Description

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.

Issue Links

• relates to: HIVE-642 udf equivalent to string split
• links to: Review Board