[ http://issues.apache.org/jira/browse/DERBY-1879?page=all ]
Daniel John Debrunner resolved DERBY-1879.
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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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