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From "A B (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-1109) lang/predicatePushdown.sql fails with wsdd5.6
Date Tue, 14 Mar 2006 01:04:54 GMT
    [ http://issues.apache.org/jira/browse/DERBY-1109?page=comments#action_12370278 ] 

A B commented on DERBY-1109:
----------------------------

This issue is the same as DERBY-1110--they both have the same query in them, and that query
is failing with the same row-ordering diff.

This diff is an interesting one: I've verified that for IBM wsdd the optimizer chooses the
same join order that it chooses for all other JVMs--which is expected since the derby.optimizer.noTimeout
flag is set to "true" for both lang/subquery.sql and lang/predicatePushdown.sql, and thus
the optimizer should always choose the same plan, regardless of machine/platform.

That said, I'm not sure what could be causing this specific difference in row ordering for
IBM wsdd.  I am able to reproduce the diff on my machine,  but don't understand where it comes
from.  Since the optimizer is choosing the same join order for all platforms, I was assuming
the row order should be the same, as well--but that's apparently not a safe assumption.  I
did notice that the queries that are failing have "DISTINCT" in them, so it's possible that
the ordering of rows based on a DISTINCT is JVM-dependent somehow, which would explain this
diff.

Can anyone confirm that one way or the other?

If this is just an _acceptable_ difference in JVM behavior, then there are two possible solutions
here: either 1) create a wsdd-specific master, or 2) (and probably more preferably) add an
"order by" clause to the queries in question to ensure that we get the same row order across
JVMs.

If, however, this difference in row order seems like incorrect behavior, then this would of
course merit further investigation.

Anyone have any input one way or the other?

> lang/predicatePushdown.sql fails with wsdd5.6
> ---------------------------------------------
>
>          Key: DERBY-1109
>          URL: http://issues.apache.org/jira/browse/DERBY-1109
>      Project: Derby
>         Type: Test
>   Components: Regression Test Failure
>     Versions: 10.2.0.0
>  Environment: IBM wsdd5.6 j9_13
>     Reporter: Deepa Remesh

>
> This test fails with the following diff:
> 7507a7508,7509
> > 2          |1          
> > 4          |2          
> 7509,7510d7510
> < 4          |2          
> < 2          |1          
> 7632a7633,7636
> > 2          |1          
> > 2          |1          
> > 4          |2          
> > 4          |2          
> 7635,7638d7638
> < 4          |2          
> < 4          |2          
> < 2          |1          
> < 2          |1     

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