Is there any hash joins in this plan? That is the standard reason to see
different ordering on different jvm/machine if plans look the same.
A B (JIRA) wrote:
[ 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
