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https://issues.apache.org/jira/browse/DERBY-5680?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13695517#comment-13695517
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Mike Matrigali commented on DERBY-5680:
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I agree with kathey, let's just backport this to 10.8 and open a new issue to
correctly handle the looping problem for soft upgrade in all versions.
Otherwise we might end up with 10.8 fixing
the problem for soft upgrade but not 10.9, 10.10 and trunk.
Hopefully we can figure out a way to handle
the buggy orphaned stat differently than the expected "disposable" stats and
deal with them differently. If you hit this problem then the problem is very
serious, as it can eat all the cpu on
at least one processor, which may be the whole machine, it also may be hard to
diagnose as those with multiple processors may just notice that "derby is slow
and slowing the rest of the
machine".
Can anyone think of a reason that the truly orphaned stat (an existing stat for
no existing index) would be useful for any previous version of the software? I
think worst case if someone had to
downgrade after we deleted the orphaned stat and it was somehow needed then
re-creating indexes would fix that issue.
> indexStat daemon processing tables over and over even when there are no
> changes in the tables
> ---------------------------------------------------------------------------------------------
>
> Key: DERBY-5680
> URL: https://issues.apache.org/jira/browse/DERBY-5680
> Project: Derby
> Issue Type: Bug
> Components: Store
> Affects Versions: 10.8.2.2, 10.9.1.0
> Reporter: Brett Bergquist
> Assignee: Kristian Waagan
> Fix For: 10.9.1.0
>
> Attachments: derby-5680-1a-drop_orphaned_stats.diff,
> derby-5680-1b-remove_disposable_stats.diff,
> derby-5680-2a-remove_redundant_check.diff,
> derby-5680-3a-rename_debug_property.diff,
> DERBY5680_backportTo108_patch1_diff.txt,
> DERBY5680_backportTo108_patch1_stat.txt
>
>
> 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.
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