RE: Update Stats slowing.....
Is this not dependant on the number of cpu vps you have ? Or has this
changed in the newer versions ?
>From what I remember, you can only have 1 update stats thread per cpu vp
-----Original Message-----
From: informix-list-bounces@iiug.org
[mailto:informix-list-bounces@iiug.org] On Behalf Of Ford, Andrew G
Sent: 17 March 2006 06:50 PM
To: malc_p@btinternet.com; informix-list@iiug.org
Subject: RE: Update Stats slowing.....
How are you running update statistics low?
If you are running a single update statistics low that contains all of
the indexed columns, you will walk the leaf pages of all 23 indexes
sequentially. I could see that taking 3 hours against a large table.
You might get better performance if you break your low run into multiple
update statistics statements and kick them off in parallel.
For example, you have:
Index 1 (a, b, c)
Index 2 (b, d, a)
Index 3 (x, y, z)
Instead of
Update statistics low for table tablename (a, b, c, d, x, y, z);
Try running the following in parallel
update statistics low for table tablename (a, b, c);
update statistics low for table tablename (b, d, a);
update statistics low for table tablename (x, y, z);
If your indexes are fragmented, setting PDQPRIORITY to 10 will let the
engine scan all of your index fragments in parallel.
PSORT_NPROCS, DBUPSPACE and PSORT_DBTEMP should have no effect on update
statistics low but will have an impact on medium and high.
Andrew Ford
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