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From "Daniel John Debrunner (JIRA)" <derby-...@db.apache.org>
Subject [jira] Resolved: (DERBY-1879) Save meta data related information for an EmbedResultSet at the plan level instead of the ResultSet level improves performance.
Date Wed, 27 Sep 2006 23:04:51 GMT
     [ http://issues.apache.org/jira/browse/DERBY-1879?page=all ]

Daniel John Debrunner resolved DERBY-1879.
------------------------------------------

    Fix Version/s: 10.3.0.0
       Resolution: Fixed

Committed revision 450607

> Save meta data related information for an EmbedResultSet at the plan level instead of
the ResultSet level improves performance.
> -------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-1879
>                 URL: http://issues.apache.org/jira/browse/DERBY-1879
>             Project: Derby
>          Issue Type: Improvement
>          Components: JDBC, Performance
>            Reporter: Daniel John Debrunner
>         Assigned To: Daniel John Debrunner
>            Priority: Minor
>             Fix For: 10.3.0.0
>
>         Attachments: derby1879_diff.txt
>
>
> EmbedResultSet creates and holds references to information that logically is at the plan
level, the same for all ResultSet's that use the same prepared plan. Holding this information
at the EmbedResultSet hurts performance and memory usage as ResultSet objects are short lived.
> Saving the ResultSetMetaData object in the ResultDescription object means a single creation
for the lifetime of the plan (shared across connections), rather than once per ResultSet object
as needed.
> Saving the column name to position mapping added in DERBY-1862 in the ResultDescription
has a similar benefit, the map is set up once per prepared plan, not once per executeQuery().
> With test changes (will attach patch soon), the performance of the derby1862 test in
DERBY-1876 improves by around 15%

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