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https://issues.apache.org/jira/browse/DRILL-4573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15222682#comment-15222682
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ASF GitHub Bot commented on DRILL-4573:
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GitHub user jcmcote opened a pull request:
https://github.com/apache/drill/pull/458
DRILL-4573: Zero copy LIKE, REGEXP_MATCHES, SUBSTR
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.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/jcmcote/drill DRILL-4573
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/drill/pull/458.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #458
----
commit 71b35ecf5895fc8fbae1bf862cbb982787712ee2
Author: jean-claude cote <[email protected]>
Date: 2016-04-02T03:37:00Z
DRILL-4573: Zero copy LIKE, REGEXP_MATCHES, SUBSTR
----
> 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
>
> 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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