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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-269) Provide some way to update index cardinality statistics (e.g. reimplement update statistics)
Date Tue, 15 Jul 2008 17:13:32 GMT

    [ https://issues.apache.org/jira/browse/DERBY-269?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12613665#action_12613665
] 

Mamta A. Satoor commented on DERBY-269:
---------------------------------------

Knut, thanks for reviewing the patch. Answers to your questions/comments
***********************
  - since the code is copied from UpdateStatisticsConstantAction, I assume USCA will be removed
from the repository in a later patch? 
Yes, I am planning on removing this file when I commit the changes.
***********************


***********************
  - UpdateStatisticsConstantAction uses a strange mix of tabs and spaces for indentation.
It would be great if the indentation is cleaned up when the code is moved. 
I took care of indentation in my codeline (sorry, it is not in the patch) in the transferred
code to AlterTableConstantAction
***********************


***********************
* - SystemProcedures.SYSCS_UPDATE_STATISTICS() uses tabs/spaces inconsistently 
I took care of indentation in my codeline (sorry, it is not in the patch).
**********************


**********************
  - comment in upgradeTests/_Suite.java has the wrong version number: 
+ {10, 4, 1, 3}, // 10.3.1.4 (April 24, 2008 / SVN 648739) 
Thanks for catching this. I fixed the version number in my codeline.
**********************


**********************
 - SYSCS_UPDATE_STATISTICS is added to Changes10_2. Shouldn't that file only test procedures
that were added in Derby 10.2? 
What I found is if I do not add SYSCS_UPDATE_STATISTICS to the list of stored procedures in
Changes10_2, I get error that there are 6 rows in SYSROUTINEPERMS but we are looking only
for 5 rows. My understanding of upgrade test is not upto date but it sounds like we are testing
the upgrade from 10.2 release to 10.5. If that is right, then I think I do need to add SYSCS_UPDATE_STATISTICS
in Changes10_2.
**********************


> 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
>         Attachments: DERBY269_update_statistics_svndiff_ver1.txt, DERBY269_update_statistics_svnstat_ver1.txt
>
>
> 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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