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From "Mike Matrigali (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-4115) Provide a way to drop statistics information
Date Tue, 24 Apr 2012 17:09:34 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4115?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13260712#comment-13260712

Mike Matrigali commented on DERBY-4115:

>t's been a while since I looked into upgrade and stored procedures. Does the restriction
above come from the fact that we can't support >the alternative behavior? That would be
to allow the procedure to be called on a soft upgraded database to remove orphaned statistics,
>and then continue using the older version afterwards. This way the problem can be fixed
without moving off the current Derby version.
>Even if the above is technically possible, I'm fine with forbidding it if it conflicts
with our current policy. I was just a bit curious :) 

I think it "might" be possible, but that we should not do it for soft upgrade.  The idea with
soft upgrade is that a user should be able to run 10.9 software in soft upgrade mode and then
go back to running 10.1 software if it is a 10.1 database.  If their application has calls
to the new drop statistics routine it is very likely not to work when run in 10.1 software
and we don't want to be supporting that.  This specific routine might work for some subset
of situation, but the policy to disable new syntax features in soft upgrade seems clean and
to easily understood behavior, rather than allow some and not others.  
> Provide a way to drop statistics information
> --------------------------------------------
>                 Key: DERBY-4115
>                 URL: https://issues.apache.org/jira/browse/DERBY-4115
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions:
>            Reporter: Kathey Marsden
>            Assignee: Mamta A. Satoor
>         Attachments: DERBY4115_patch1_diff.txt
> Now that DERBY-269 has been resolved,  users can update statistics, but once they do,
they are committed to using and maintaining the statistics, even if it doesn't improve performance
or they have difficulty maintaining the statistics on a regular basis.  It would be good to
have a way to drop statistics information so that users could revert to the prior behavior
if needed.

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