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From "Daniel John Debrunner (JIRA)" <derby-...@db.apache.org>
Subject [jira] Created: (DERBY-909) Improve performance of String literals in statements
Date Wed, 01 Feb 2006 18:40:24 GMT
Improve performance of String literals in statements
----------------------------------------------------

         Key: DERBY-909
         URL: http://issues.apache.org/jira/browse/DERBY-909
     Project: Derby
        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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