[DERBY-5680] indexStat daemon processing tables over and over even when there are no changes in the tables

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 10.8.2.2, 10.9.1.0
• Fix Version/s: 10.8.3.3, 10.9.1.0
• Component/s: Store
• Bug behavior facts: Performance, Seen in production
• Assignee: Kristian Waagan
• Reporter: Brett Bergquist
• Created: 30/Mar/12 17:20
• Updated: 03/Sep/14 08:31
• Resolved: 28/Jun/13 18:25

Description

I think there is something wrong with the indexStats.

The problem happens on many tables in the database.
None of these tables are changing however, no inserts or deletes or updates. They are being queried, however.

Here is one such table.

Here is the statistics for this table:

Table (Index) 2 3
ACCOUNTTABLE_CONFIG_BUNDLE (SQL081029110443810) numunique= 38390 numrows= 38390 2012-03-30 13:00:26.84
ACCOUNTTABLE_CONFIG_BUNDLE (SQL100922215819290) numunique= 38390 numrows= 38390 2012-03-30 13:00:26.917

There are in fact 38390 rows in the table.

Here is some of the indexStat trace:

Fri Mar 30 12:47:12 EDT 2012 Thread[DRDAConnThread_43,5,main]

{istat} "PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": update scheduled, reason=[t-est=38390, i-est=2355 => cmp=2.7912562815443245] (queueSize=12)
Fri Mar 30 12:47:48 EDT 2012 Thread[index-stat-thread,5,main] {istat}

"PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": wrote stats for index SQL081029110443810 (fc33890d-011d-491f-3d8c-0000376d74d3): rows=38390, card=[38390]
Fri Mar 30 12:47:48 EDT 2012 Thread[index-stat-thread,5,main]

{istat} "PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": wrote stats for index SQL100922215819290 (75608675-012b-3c38-b55c-000043ea6398): rows=38390, card=[38390]
Fri Mar 30 12:47:48 EDT 2012 Thread[index-stat-thread,5,main] {istat}

"PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": scan durations (c30625=91ms,c30625=98ms)
Fri Mar 30 12:47:48 EDT 2012 Thread[index-stat-thread,5,main]

{istat} "PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": generation complete (210 ms)

Fri Mar 30 12:47:49 EDT 2012 Thread[DRDAConnThread_44,5,main] {istat}

"PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": update scheduled, reason=[t-est=38390, i-est=2355 => cmp=2.7912562815443245] (queueSize=19)
Fri Mar 30 12:48:25 EDT 2012 Thread[index-stat-thread,5,main]

{istat} "PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": wrote stats for index SQL081029110443810 (fc33890d-011d-491f-3d8c-0000376d74d3): rows=38390, card=[38390]
Fri Mar 30 12:48:25 EDT 2012 Thread[index-stat-thread,5,main] {istat}

"PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": wrote stats for index SQL100922215819290 (75608675-012b-3c38-b55c-000043ea6398): rows=38390, card=[38390]
Fri Mar 30 12:48:25 EDT 2012 Thread[index-stat-thread,5,main]

{istat} "PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": scan durations (c30625=93ms,c30625=95ms)
Fri Mar 30 12:48:25 EDT 2012 Thread[index-stat-thread,5,main] {istat}

"PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": generation complete (211 ms)
Fri Mar 30 12:48:25 EDT 2012 Thread[DRDAConnThread_50,5,main]

{istat} "PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": update scheduled, reason=[t-est=38390, i-est=2355 => cmp=2.7912562815443245] (queueSize=18)

Fri Mar 30 12:48:57 EDT 2012 Thread[index-stat-thread,5,main] {istat}

"PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": wrote stats for index SQL081029110443810 (fc33890d-011d-491f-3d8c-0000376d74d3): rows=38390, card=[38390]
Fri Mar 30 12:48:57 EDT 2012 Thread[index-stat-thread,5,main]

{istat} "PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": wrote stats for index SQL100922215819290 (75608675-012b-3c38-b55c-000043ea6398): rows=38390, card=[38390]
Fri Mar 30 12:48:57 EDT 2012 Thread[index-stat-thread,5,main] {istat}

"PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": generation complete (243 ms)

Fri Mar 30 12:49:27 EDT 2012 Thread[DRDAConnThread_56,5,main]

{istat} "PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": update scheduled, reason=[t-est=38390, i-est=2355 => cmp=2.7912562815443245] (queueSize=20)
Fri Mar 30 12:49:36 EDT 2012 Thread[index-stat-thread,5,main] {istat}

"PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": wrote stats for index SQL081029110443810 (fc33890d-011d-491f-3d8c-0000376d74d3): rows=38390, card=[38390]
Fri Mar 30 12:49:37 EDT 2012 Thread[index-stat-thread,5,main]

{istat} "PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": wrote stats for index SQL100922215819290 (75608675-012b-3c38-b55c-000043ea6398): rows=38390, card=[38390]
Fri Mar 30 12:49:37 EDT 2012 Thread[index-stat-thread,5,main] {istat}

"PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": scan durations (c30625=111ms,c30625=108ms)
Fri Mar 30 12:49:37 EDT 2012 Thread[index-stat-thread,5,main]

{istat} "PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": generation complete (238 ms)

Fri Mar 30 12:49:37 EDT 2012 Thread[DRDAConnThread_49,5,main] {istat}

"PKG_9145E_V1"."ACCOUNTTABLE_CONFIG_BUNDLE": update scheduled, reason=[t-est=38390, i-est=2355 => cmp=2.7912562815443245] (queueSize=18)

As can be seen, the "i-est" appears to be wrong and is used over and over even though the statistics for the indexes have been updated.

Issue Links

• 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
• relates to: DERBY-6283 indexStat daemon processing tables over and over even when there are no changes in the tables in soft upgraded database.