update statistics
Each night we run update statistics with the following
sql statement:
update systables set npused = nrows /
(2020/(rowsize)+4)
where npused < 0
and the result log file give us the following output:
============================
Mon Jan 24 22:30:03 EST 2000
0 row(s) updated.
============================
I am a UNIX SYS ADMIN and have recently taken on the
task of DBA, and have realy very little knowledge of
this. Can anyone tell me by looking at the statements
above if this is correct and why is the output log
giving us 0 row(s) updated after it ran for almost 8
hours. Our database is 26gig strong, this in on
informix version 5.10uc5 and hp-ux version 10.20. Any
comments and/or suggestions are welcome.
David Kulkarni
dnk61@yahoo.com
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This is NOT running update statistics. There was a bug in an early 7.2x
release of IDS that under certain
circumstances would set the npused to -1 or other negative values. This
confused the optimizer. The
update you are running simply corrects the damage. See the Performance
Guide manual (available
online) for the recommended suite of UPDATE STATISTICS commands you
should be running
periodically (nightly is overkill). You can also get my dostats.ec
utility which is contained in the package
utils2_ak available from the IIUG Software Repository, or one of the
several scripts available in the
repository. These all try to implement the protocols described in the
Performance Guide with varying
degrees of success and with varying levels of configuration possible.
Art S. Kagel
David Kulkarni wrote:
> Each night we run update statistics with the following
> sql statement:
>
> update systables set npused = nrows /
> (2020/(rowsize)+4)
> where npused < 0>
> and the result log file give us the following output:
>
> ============================
> Mon Jan 24 22:30:03 EST 2000
>
> 0 row(s) updated.
>
> ============================
>
> I am a UNIX SYS ADMIN and have recently taken on the
> task of DBA, and have realy very little knowledge of
> this. Can anyone tell me by looking at the statements
> above if this is correct and why is the output log
> giving us 0 row(s) updated after it ran for almost 8
> hours. Our database is 26gig strong, this in on
> informix version 5.10uc5 and hp-ux version 10.20. Any
> comments and/or suggestions are welcome.
>
> David Kulkarni
> dnk61@yahoo.com
>
> __________________________________________________
> Do You Yahoo!?
> Talk to your friends online with Yahoo! Messenger.
> http://im.yahoo.com