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https://issues.apache.org/jira/browse/DRILL-4573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15263382#comment-15263382
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ASF GitHub Bot commented on DRILL-4573:
---------------------------------------

Github user jcmcote commented on the pull request:

    https://github.com/apache/drill/pull/458#issuecomment-215608196
  
    Hey Sean,
    
    You did not apply the correct patch. I made the code review changes you 
asked and updated the patch in the jira ticket. But somehow the code that made 
it into the git repo is the initial patch.
    
    Have a look at the one in the jira ticket you will see it has comments in 
the CharSequenceWrapper.


> Zero copy LIKE, REGEXP_MATCHES, SUBSTR
> --------------------------------------
>
>                 Key: DRILL-4573
>                 URL: https://issues.apache.org/jira/browse/DRILL-4573
>             Project: Apache Drill
>          Issue Type: Improvement
>            Reporter: jean-claude
>            Priority: Minor
>             Fix For: 1.7.0
>
>         Attachments: DRILL-4573.patch.txt
>
>
> All the functions using the java.util.regex.Matcher are currently creating 
> Java string objects to pass into the matcher.reset().
> However this creates unnecessary copy of the bytes and a Java string object.
> The matcher uses a CharSequence, so instead of making a copy we can create an 
> adapter from the DrillBuffer to the CharSequence interface.
> Gains of 25% in execution speed are possible when going over VARCHAR of 36 
> chars. The gain will be proportional to the size of the VARCHAR.



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