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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-269) Provide some way to update index cardinality statistics (e.g. reimplement update statistics)
Date Fri, 27 Jun 2008 11:15:45 GMT

    [ https://issues.apache.org/jira/browse/DERBY-269?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12608726#action_12608726
] 

Knut Anders Hatlen commented on DERBY-269:
------------------------------------------

I would have preferred a single procedure with two parameters, schemaname and table_or_index_name.
But since it's not possible to say whether the table or the index was meant if there's an
index that has the same name as a table, I guess that's not an option. Having a single procedure
allows us to have simpler procedure names, but I agree that it's not so clear with the three
parameters.

As to the naming of the different procedures, could we pick one of them that the users are
more likely to run and give a simpler name? For instance:
  SYSCS_UPDATE_STATISTICS - update one named index
  SYSCS_UPDATE_STATISTICS_ALL - update all indexes on a table

One more thing about procedure naming. I know that all the existing procedures in SYSCS_UTIL
have names starting with SYSCS_ and cannot be changed. But the SYSCS_ prefix is redundant
and makes the names unnecessarily long, so perhaps we could skip it for new procedures?

> Provide some way to update index cardinality statistics (e.g. reimplement update statistics)
> --------------------------------------------------------------------------------------------
>
>                 Key: DERBY-269
>                 URL: https://issues.apache.org/jira/browse/DERBY-269
>             Project: Derby
>          Issue Type: New Feature
>          Components: SQL
>    Affects Versions: 10.0.2.0, 10.0.2.1, 10.1.1.0, 10.2.2.0, 10.3.1.4
>            Reporter: Stan Bradbury
>            Assignee: Mamta A. Satoor
>
> Performance problems are being reported that can be resolved by updating the cardinality
statistics used by the optimizer.  Currently the only time the statistics are guaranteed to
be an up-to-date is when the index is first created on a fully populated table.  This is most
easily accomplished on an existing table by using the command: 
>    alter table <table-name> compress [sequential]  
> Compress table is an I/O intensive task.  A better way to achieve this would be to re-enable
parser support for the 'update statistics' command or re-implement the update in some other
fashion.

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