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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:
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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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