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From Andrew Bruno <andrew.br...@gmail.com>
Subject Re: SELECT query takes 5 secs, what can I do?
Date Fri, 18 Sep 2009 00:31:15 GMT
Hey all,

Sorry been flat chat for a while, but I gotta say that the query
improved dramatically when the stats updated.

When I created the index, I didnt wait for the stats to be updated.

I came back the next day, and the query was running in sub seconds.
Now ExchangeSync can run well again on this 3G database.

I want to thank everyone for the awesome support, including some of
those left or right field ideas!

Cheers
Andrew


On Thu, Sep 17, 2009 at 7:26 PM, Knut Anders Hatlen <Knut.Hatlen@sun.com> wrote:
> Brett Wooldridge <brett.wooldridge@gmail.com> writes:
>
>> You can force Derby to update statistics with this command:
>>
>> alter table <table-name> compress [sequential]
>>
>> Note this command itself might take a long time -- dozens of minutes -- but in
>> a system like yours you could get away with running it once or month or so at
>> some off-peak time.
>
> In Derby 10.5 you have a cheaper way of updating the index cardinality
> statistics. This statement will update the statistics for all the
> indexes on columns in MYSCHEMA.MYTABLE without doing an expensive
> compress:
>
>  CALL SYSCS_UTIL.SYSCS_UPDATE_STATISTICS('MYSCHEMA', 'MYTABLE', NULL)
>
> http://db.apache.org/derby/docs/10.5/ref/rrefupdatestatsproc.html
>
> --
> Knut Anders
>

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