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https://issues.apache.org/jira/browse/DERBY-4112?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mamta A. Satoor updated DERBY-4112:
-----------------------------------
Urgency: Normal
Labels: derby_triage10_10 (was: )
> Make it possible to execute a statement with all considered plans
> -----------------------------------------------------------------
>
> Key: DERBY-4112
> URL: https://issues.apache.org/jira/browse/DERBY-4112
> Project: Derby
> Issue Type: Improvement
> Components: SQL, Test
> Affects Versions: 10.6.1.0
> Reporter: Kathey Marsden
> Priority: Minor
> Labels: derby_triage10_10
>
> Often we have bugs that occur only if a specific query plan is selected.
> These are often hard to reproduce or require a great deal of setup to
> reproduce the exact conditions of the failed execution (for example
> DERBY-3926). It would be very helpful for debugging user reports and also
> for expanding our testing, if there was a way to execute a query repeatedly
> with the different plans considered and identify the failing one.
> It would be slow, but Mike suggested maybe we could use optimizer directives
> to do this. If the query plans were numbered from 1 to the number considered
> and then you had a directive --DERBY-PROPERTIES QUERYPLAN=<N> where N is the
> sequential number of the plan considered, the statement would just execute
> as soon as it had considered that many plans. It could throw an exception if
> N exceeded the number of considered plans.
> The calling test code could then just iterate until it identified the
> failing plan and look for the exception to know it was finished. If there
> was a problem with a plan the developers could reliably re-execute with the
> failing plan to debug.
> I think this could be a newcomer task with some guidance and would be a good
> low risk opportunity to learn about the optimizer.
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