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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-4112) Make it possible to execute a statement with all considered plans
Date Sun, 30 Sep 2012 01:36:07 GMT

     [ https://issues.apache.org/jira/browse/DERBY-4112?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

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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