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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-4115) Provide a way to drop statistics information
Date Thu, 26 Apr 2012 21:52:51 GMT

     [ https://issues.apache.org/jira/browse/DERBY-4115?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Mamta A. Satoor updated DERBY-4115:
-----------------------------------

    Attachment: DERBY4115_patch4_diff.txt

Attaching patch, DERBY4115_patch4_diff, which is same as previous patch but now has changes
to sqlgrammar.,jj to recognize the internal syntax ALTER TABLE tablename ALL DROP STATISTICS
or ALTER TABLE tablename DROP STATISTICS indexname. Currently, this just calls the code for
update statistics. This is of course wrong but I wanted to see that the basic framework to
support new syntax works in the grammar.

Next, I plan to change the new procedure to actually send the ALTER TABLE DROP STATISTICS
call when the procedure is invoked.

After thatt, I plan to make changes so that we call some dummy code(as the first step) in
alter table when DROP STATISTICS is requested by the new stored procedure through the sql
grammar..
                
> 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: 10.6.1.0
>            Reporter: Kathey Marsden
>            Assignee: Mamta A. Satoor
>         Attachments: DERBY4115_patch1_diff.txt, DERBY4115_patch2_diff.txt, DERBY4115_patch3_diff.txt,
DERBY4115_patch4_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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