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https://issues.apache.org/jira/browse/PIG-965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12790928#action_12790928
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Thejas M Nair commented on PIG-965:
-----------------------------------
The new patch does not address the following comment -
* RegexInit.java, in determineBestRegexMethod Line 85 - 120
There are while loops where we are testing only for preceding '\'
For example -
${code}
if( index != 0 ) {
while( pattern.charAt(index -1 ) == '\\' ) {
index = pattern.indexOf('[');
}
${code}
Should be -
${code}
if( index != 0 ) {
while( isCharEscaped(pattern,index) ) {
index = pattern.indexOf('[');
}
${code}
There are 3 such while loops between lines 68-96 (in new patch) that needs to
be fixed.
* The indentation in RegexInit.isCharEscaped needs to be fixed.
Everything else looks good.
> PERFORMANCE: optimize common case in matches (PORegex)
> ------------------------------------------------------
>
> Key: PIG-965
> URL: https://issues.apache.org/jira/browse/PIG-965
> Project: Pig
> Issue Type: Improvement
> Components: impl
> Reporter: Thejas M Nair
> Assignee: Ankit Modi
> Attachments: automaton.jar, poregex2.patch
>
>
> Some frequently seen use cases of 'matches' comparison operator have follow
> properties -
> 1. The rhs is a constant string . eg "c1 matches 'abc%' "
> 2. Regexes such that look for matching prefix , suffix etc are very common.
> eg - "abc%', "%abc", '%abc%'
> To optimize for these common cases , PORegex.java can be changed to -
> 1. Compile the pattern (rhs of matches) re-use it if the pattern string has
> not changed.
> 2. Use string comparisons for simple common regexes (in 2 above).
> The implementation of Hive like clause uses similar optimizations.
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