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From "Christopher Saunders (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-909) Improve performance of String literals in statements
Date Fri, 28 Mar 2008 16:24:24 GMT

    [ https://issues.apache.org/jira/browse/DERBY-909?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12583083#action_12583083

Christopher Saunders commented on DERBY-909:

I am interested as taking this as a project for the Summer of Code.  Would this be a good
project on its own, or should I bundle this together with re-writing test cases or fixing

> Improve performance of String literals in statements
> ----------------------------------------------------
>                 Key: DERBY-909
>                 URL: https://issues.apache.org/jira/browse/DERBY-909
>             Project: Derby
>          Issue Type: Improvement
>          Components: Newcomer, SQL
>            Reporter: Daniel John Debrunner
>            Priority: Minor
> String literals (constants) go through this process currently
> Create String object from within parser
> Serialized String into generated class file as UTF-8 (taking up two constant pool entries)
> Unserialize and intern String from generated class at class load time
> The serialize into the class file and un-serialize can be avoided by saving  the String
in the saved object pool (see CompilerContext)
> This would benefit the common pattern we see in SQL scripts that load data like:
> insert into customer values (1, 'Fred', 'Flintstone');
> insert into customer values (2, 'Wilma'', 'Flintstone');
> etc.
> etc.
> Note these are poor performing in Derby compared to other databases.
> It would also be a step on the way to having a single compiled plan for such statements
that don't use parameter markers.
> Most likely the performance benefit with inserts will be small until DERBY-888 is fixed,
because with inserts the sync of the allocated pages dominates the cost.
> Possible newcomer task with guideance.

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