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https://issues.apache.org/jira/browse/DERBY-3788?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mike Matrigali updated DERBY-3788:
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I don't know if any of these are good ideas but maybe someone with knowledge of
code can discuss. They are
options that came to mind:
1) explore why the error is happening and see if updating stats can be special
cased. It is different than a
"real" ddl that might cause havoc changing during a comple.
2) rather than update the stat, just inline calculate and use that for current
compile and schedule a later task after
compile to do the update.
3) give up on updating during compile and just use default, but schedule update
after compile and somehow mark query to be recompiled again the next time (this
might automatically happen if update of statistic already causes dependency to
change on compiled query - i don't know.
4) when you find missing stat, give up on current compile, update stat, and
then retry the compile.
As I understood it, you were looking at inline update of stats as a incremental
dev step - maybe it is not worth it
given the problems and you should jump to long term strategy of delaying
update.
> 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: New Feature
> Components: Performance
> Affects Versions: 10.5.0.0
> Reporter: Mamta A. Satoor
> Assignee: Mamta A. Satoor
>
> 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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