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From "jean-claude (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (DRILL-4573) Zero copy LIKE, REGEXP_MATCHES, SUBSTR
Date Sun, 01 May 2016 16:24:12 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15265318#comment-15265318
] 

jean-claude edited comment on DRILL-4573 at 5/1/16 4:23 PM:
------------------------------------------------------------

I attached patch DRILL-4573-3

It fixes the issue reported DRILL-4645

The CharSequenceWrapper.toString() method was called.

I decided to in-line the Matcher.replaceAll() to avoid creating that String altogether.

Notice in the case there is nothing to replace I just re-use the input buffer.



was (Author: jccote):
I attached patch DRILL-4573-3

It fixes the issue reported DRILL-4645

The CharSequenceWrapper.toString() method was called.

I decided to in-line the Matcher.replaceAll() to avoid creating that String altogether.

Notice in the case there is nothing to replace I copy the input buffer into the output buffer.
Can you confirm that is the best way to copy the input buffer into the output buffer?



> 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-4573-3.patch.txt, 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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