[DERBY-6283] indexStat daemon processing tables over and over even when there are no changes in the tables in soft upgraded database.

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 10.8.3.3, 10.9.2.2, 10.10.2.0, 10.11.1.1
• Fix Version/s: 10.8.3.3, 10.9.2.2, 10.10.2.0, 10.11.1.1
• Component/s: Store
• Labels: derby_triage10_11
• Issue & fix info: High Value Fix, Patch Available
• Bug behavior facts: Performance
• Assignee: Mike Matrigali
• Reporter: Mike Matrigali
• Created: 28/Jun/13 16:54
• Updated: 21/Jan/15 00:23
• Resolved: 04/Nov/13 21:34

Description

The fix for DERBY-5680 currently requires hard upgrade. A soft upgrade database with an orphaned stat row, that can be caused by something like DERBY-5681, will cause DERBY to spin eating up 100% of a cpu and possibly all the disk bandwith of the disk where the database is located.

We should implement a fix that can be applied to soft upgraded databases if at all possible.

In soft upgraded databases we can no use the work around of dropping the statistics as it is not available
to soft upgraded db's with version < 10.9. The only current workaround is to disable background stats
completely. Dropping and recreating the suspect table may also work.

Issue Links

• is related to: DERBY-5680 indexStat daemon processing tables over and over even when there are no changes in the tables
• is related to: DERBY-5681 When a foreign key constraint on a table is dropped, the associated statistics row for the conglomerate is not removed
• is related to: DERBY-3790 Investigate if request for update statistics can be skipped for certain kind of indexes, one instance may be unique indexes based on one column.