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https://issues.apache.org/jira/browse/DERBY-3479?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12575050#action_12575050
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A B commented on DERBY-3479:
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> The predicatePushdown test is known to be unstable due to varying query plans
True, though I don't think this particular difference has ever shown up before?
Usually the diffs are rather large, but this one is relatively small--the join
order of two tables for a single query has been switched, and that's it.
> Rewriting the unstable parts of the test in JUnit and only check the relevant
> parts
> of the query plan sounds like a reasonable approach to me.
I agree. Probably not a trivial task, but one worth doing if anyone is so
inclined.
The question of *why* we intermittently get different plans even though the
"noTimeout" property is set to true remains a mystery. And in particular, how
does the buffer manager come into play for optimizer path decisions? But
that's probably a separate issue; fixing the predicatePushdown test by
converting it to JUnit seems like a good move regardless.
> Changed/unexpected query plan when running test 'lang/predicatePushdown.sql'
> ----------------------------------------------------------------------------
>
> Key: DERBY-3479
> URL: https://issues.apache.org/jira/browse/DERBY-3479
> Project: Derby
> Issue Type: Bug
> Components: Regression Test Failure
> Affects Versions: 10.4.0.0
> Environment: OS: Solaris 10 6/06 s10x_u2wos_09a X86 64bits - SunOS
> 5.10 Generic_118855-14
> JVM: Sun Microsystems Inc., java version "1.6.0_04", Java(TM) SE Runtime
> Environment (build 1.6.0_04-b12), Java HotSpot(TM) Client VM (build 10.0-b19,
> mixed mode)
> Reporter: Ole Solberg
>
> Seen in tinderbox since r631930.
> See e.g.
> http://dbtg.thresher.com/derby/test/tinderbox_trunk16/jvm1.6/testing/testlog/SunOS-5.10_i86pc-i386/631932-derbyall_diff.txt
> :
> *** Start: predicatePushdown jdk1.6.0_04 derbyall:derbylang 2008-02-28
> 14:02:49 ***
> 9285 del
> < Rows seen from the left = 20
> 9285a9285
> > Rows seen from the left = 10
> 9297 del
> < Rows seen from the right = 20
> 9297a9297
> > Rows seen from the right = 10
> 9299 del
> < Rows returned = 20
> 9299a9299
> > Rows returned = 10
> .
> .
> .
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