[DERBY-4661] Reduce size of encoding buffer for short character values

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 10.7.1.1
• Fix Version/s: 10.5.3.1, 10.6.2.1, 10.7.1.1
• Component/s: JDBC
• Labels: CLOB
• Environment: Inserts using setXStream(int, Reader/InputStream, int/long) for short values on character columns
• Bug behavior facts: Performance
• Assignee: Kristian Waagan
• Reporter: Kristian Waagan
• Created: 14/May/10 11:54
• Updated: 29/Nov/10 14:21
• Resolved: 25/May/10 15:12

Description

When inserting character values Derby converts from Java char to an on-disk encoding of UTF-8. To to this, the user stream is read and the resulting bytes after conversion are placed in a "translation buffer". The default size of the buffer is 32 KB. When inserting a lot of short values, the pressure on the Java garbage collector is unnecessary high and the allocation/GC also causes a somewhat higher CPU usage.

This effect of this issue can easily be reduced by sizing the buffer in the appropriate cases.