Serious Performance Drop on AIX

[Ahmet Bilgili]

Hi,

We have been using a long select-subselect query on a db2 server on
aix , the operation was taking nearly 4 minutes , but a mystical kind
of thing happened which we dont know, and the query started to take 6
hours , but mystically again by using the exported data from the aix
takes 6-10 minutes on the windows server.We couldnt explain the
situation. Any ideas ?

Ahmet Bilgili

[Serge Rielau]

Compare the plans from Windows against AIX.

Cheers
Serge
--
Serge Rielau
DB2 SQL Compiler Development
IBM Toronto Lab

[Ian]

Ahmet Bilgili wrote:

Hi,

We have been using a long select-subselect query on a db2 server on
aix , the operation was taking nearly 4 minutes , but a mystical kind
of thing happened which we dont know, and the query started to take 6
hours , but mystically again by using the exported data from the aix
takes 6-10 minutes on the windows server.We couldnt explain the
situation. Any ideas ?

Ahmet Bilgili

Did you statistics get updated on the AIX box?

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[Jochen Luebbers]

Sounds like your table(s) are in a mess. Try to reorganise them,
or export them drop them and re-import again.

HTH

J. Luebbers
--
Jochen Lübbers lu******@tde-online.de
Software Development Group I TDE - Tele Data Electronic GmbH
"Who desire to give up freedom in order to gain security
will loose both in the end." (Benjamin Franklin)

[Ahmet Bilgili]

Ian <ia*****@mobileaudio.com> wrote in message news:<40********@corp.newsgroups.com>...

Ahmet Bilgili wrote:

Hi,

We have been using a long select-subselect query on a db2 server on
aix , the operation was taking nearly 4 minutes , but a mystical kind
of thing happened which we dont know, and the query started to take 6
hours , but mystically again by using the exported data from the aix
takes 6-10 minutes on the windows server.We couldnt explain the
situation. Any ideas ?

Ahmet Bilgili
Did you statistics get updated on the AIX box?

We have reorganized the tables, nothing have changed , what about the
statistics , is there a special thing we must throw our attentions on
in the statistics ?


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[Larry]

See the RUNSTATS command.

Larry Edelstein

Ahmet Bilgili wrote:

Ian <ia*****@mobileaudio.com> wrote in message news:<40********@corp.newsgroups.com>...

Ahmet Bilgili wrote:

Hi,

We have been using a long select-subselect query on a db2 server on
aix , the operation was taking nearly 4 minutes , but a mystical kind
of thing happened which we dont know, and the query started to take 6
hours , but mystically again by using the exported data from the aix
takes 6-10 minutes on the windows server.We couldnt explain the
situation. Any ideas ?

Ahmet Bilgili

Did you statistics get updated on the AIX box?

We have reorganized the tables, nothing have changed , what about the
statistics , is there a special thing we must throw our attentions on
in the statistics ?

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[Steve]

> >

We have reorganized the tables, nothing have changed , what about the
statistics , is there a special thing we must throw our attentions on
in the statistics ?

We experienced something similar on v7.2. We loaded about 250 MB of
data, then all of the sudden a 20 second sql took 20 minutes. We had
to set the qry opt to 1 from 5. Reorgs and runstats did nothing to
help. It seems the optimizer finally went over some threshhold with
the new stats from the extra data. The DB is smallish - around 5 GB.

Hope this helps.