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From "Jinfeng Ni (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4573) Zero copy LIKE, REGEXP_MATCHES, SUBSTR
Date Tue, 31 May 2016 18:46:13 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15308331#comment-15308331
] 

Jinfeng Ni commented on DRILL-4573:
-----------------------------------

If there is no faster way, I think 7% overhead is the necessary cost Drill has to pay to get
things correct, without forcing user to tell Drill whether the input is ASCII only or not.
Even with this 7% overhead, it still shows 17% improvement, which is good thing. 

Can you please wrap what you have so far, and submit a new pull request or patch?  

> 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: Critical
>             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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