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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] Resolved: (DERBY-3788) Provide a zero-admin way of updating the statisitcs of an index
Date Sun, 06 Mar 2011 11:43:45 GMT

     [ https://issues.apache.org/jira/browse/DERBY-3788?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kristian Waagan resolved DERBY-3788.
------------------------------------

       Resolution: Duplicate
    Fix Version/s: 10.8.0.0

Resolving as duplicate (see comment above for the relevant JIRAs).

> Provide a zero-admin way of updating the statisitcs of an index
> ---------------------------------------------------------------
>
>                 Key: DERBY-3788
>                 URL: https://issues.apache.org/jira/browse/DERBY-3788
>             Project: Derby
>          Issue Type: Improvement
>          Components: Store
>    Affects Versions: 10.5.1.1
>            Reporter: Mamta A. Satoor
>            Assignee: Mamta A. Satoor
>             Fix For: 10.8.0.0
>
>         Attachments: DERBY3788_patch1_diff.txt, DERBY3788_patch1_stat.txt, DERBY3788_patch2_diff.txt,
DERBY3788_patch2_stat.txt, DERBY3788_patch3_diff.txt, DERBY3788_patch3_stat.txt, DERBY3788_update_all_missing_stats_after_bind_patch4_diff.txt,
DERBY3788_update_all_missing_stats_after_bind_patch4_stat.txt, DERBY_3788_Mgr.java, DERBY_3788_Repro.java
>
>
> DERBY-269 provided a manual way of updating the statistics using the new system stored
procedure SYSCS_UTIL.SYSCS_UPDATE_STATISTICS. It will be good for Derby to provide an automatic
way of updating the statistics without requiring to run the stored procedure manually. There
was some discussion on DERBY-269 about providing the 0-admin way. I have copied it here for
reference.
> *********************
> Kathey Marsden - 22/May/05 03:53 PM 
> Some sort of zero admin solution for updating statistics would be prefferable to the
manual 'update statistics' 
> *********************
> *********************
> Mike Matrigali - 11/Jun/08 12:37 PM 
> I have not seen any other suggestions, how about the following zero admin solution? It
is not perfect - suggestions welcome. 
> Along with the statistics storing, save how many rows were in the table when exact statistics
were calculated. This number is 0 if none have been calculated because index creation happened
on an empty table. At query compile time when we look up statistics we automatically recalculate
the statistics at certain threshholds - say something like row count growing past next threshhold
: 10, 100, 1000, 100000 - with upper limit being somewhere around how many rows we can process
in some small amount of time - like 1 second on a modern laptop. If we are worried about response
time, maybe we background queue the stat gathering rather than waiting with maybe some quick
load if no stat has ever been gathered. The background gathering could be optimized to not
interfere with locks by using read uncommitted. 
> I think it would be useful to also have the manual call just to make it easy to support
customers and debug issues in the field. There is proably always some dynamic data distribution
change that in some case won't be picked up by the automatic algorithm. Also just very useful
for those who have complete control of the create ddl, load data, run stats, deliver application
process. 
> *********************

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