[DERBY-3934] Improve performance of reading modified Clobs

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 10.5.1.1
• Fix Version/s: 10.5.1.1
• Component/s: JDBC
• Bug behavior facts: Performance
• Assignee: Kristian Waagan
• Reporter: Kristian Waagan
• Created: 05/Nov/08 10:41
• Updated: 04/May/09 18:22
• Resolved: 02/Mar/09 12:23

Description

The performance of reading modified Clobs is poor, which is demonstrated by running a test program selecting a 10 MB Clob and then getting the contents using getSubString:

• unmodified Clob (StoreStreamClob) : ~1 300 ms
• modified Clob (TemporaryClob): ~156 000 ms

In this case, the Clob was modified by changing the first character.

A number of subtasks will be created to handle the various issues, which will be related to both performance and code cleanup.
For a brief overview, see http://www.nabble.com/Suggestion-for-improving-ClobUpdatableReader-and-related-code-to20308303.html