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From "Daniel John Debrunner (JIRA)" <derby-...@db.apache.org>
Subject [jira] Created: (DERBY-1879) Save meta data related information for an EmbedResultSet at the plan level instead of the ResultSet level improves performance.
Date Fri, 22 Sep 2006 17:55:22 GMT
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


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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