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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3787) Document the new system stored procedure SYSCS_UTIL.SYSCS_UPDATE_STATISTICS which was added as part of DERBY-269
Date Fri, 06 Mar 2009 16:55:56 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3787?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12679646#action_12679646
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Mamta A. Satoor commented on DERBY-3787:
----------------------------------------

Thanks for working on this jira entry, Laura.

Here are my suggestions to your questions.

1)Maybe something like following can be used to describe this procedure(please feel free to
reword following)
Updates cardinality statistics (or creates them if they do not exist) for a table's index
or for all the indexes on a table. Derby uses cardinality statistics to determine optimal
query plan during the compilation of a query. If the statistics are missing, Derby may end
up using a query plan which is not
the most efficient plan.

2)As for example, feel free to change the table names etc, but here are couple
Following will create(if missing)/update statistics from index PAY_DESC on SAMP.EMPLOYEE.
call SYSCS_UTIL.SYSCS_UPDATE_STATISTICS('SAMP', 'EMPLOYEE', 'PAY_DESC');
Following will create(if missing)/update statistics on all the indexes on SAMP.EMPLOYEE.
call SYSCS_UTIL.SYSCS_UPDATE_STATISTICS('SAMP', 'EMPLOYEE', null);

3)The results of running the procedure can be seen by what query plan was picked for a given
query. I am not sure we want to copy the whole query plan for the 2 scenarios(before and after
updating the statistics). If we decide to include the query plan in the doc, we will have
to make sure that we
maintain it between the releases in case the query plan format changes between the releases.

Hope this helps.

> Document the new system stored procedure SYSCS_UTIL.SYSCS_UPDATE_STATISTICS which was
added as part of DERBY-269
> ----------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-3787
>                 URL: https://issues.apache.org/jira/browse/DERBY-3787
>             Project: Derby
>          Issue Type: Task
>          Components: Documentation
>    Affects Versions: 10.5.0.0
>            Reporter: Mamta A. Satoor
>            Assignee: Laura Stewart
>
> DERBY-269 added a new system stored procedure in Derby 10.5 to provide the users a way
to update the statistics for all the indexes or one specific index on a table. We should document
this in our documentation.

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