Re: Slow system after rebuilding tables

In article <6i7aks$ltk@newsb.netnews.att.com>, Paul Finkel <pfinkel@cbs1.att.com> writes >My system (instance of ONLINE) and the machine (NCR 3435) are running very >slowly. >History: > >on 4/23/98 we dumped the data from two of our major tables ("case" and >"person") >modified the text files to accomodate the change to the tables >rebuilt the tables with the modified schemas and reloaded data. >Then we rebuilt indexes. > >The "case" table is in its own dbspace, the "person" table is in the dbspace >set aside for the rest of the database. The root dbspace is seperate from >the other two dbspaces. The only thing that I know of that is different from >before (other than two new fields) is that when I built the "case" table in >its own dbspce, I created the first extent with a size just a little smaller >than the size of the dbsapce at the suggestion of Informix tech support. >That seems to make sense to me: one big extent. > >Another note: the "case" dbspace and the "production" dbspace (the rest of >the database) are on seperate slices, but on the same disk device, however >they were that way before the migration of the data took place. > >Now, in addition to the users complaining about the speed of simsply >queries, if I run >the UNIX command "ps -ef|grep oninit" I see that the oninits associated with >this instance that are "cpu" threads have very long run times. > >If I run the UNIX command "sar -d 1 10" to look at the devices, I see that >the device that the two dbspaces is on has very high average usage >(90 -100%). Obviously that indicates a slow down. > >Why would the changes to those two tables that I made be slowing things >down? The new fields didn't increase the size of the data substantially. >Here is another piece of information: users are reporting that reports >(which almost always involve the "case" table) are being returned quickly. >That makes sense consdiering that the "case" data is contiguous. Why is the >device taking such a hit? (I am planning to move data around at some future >date, but it won't be easy due to limited resources) > >Please respond by e-mail and post. > Have you run update statistics on the two tables? >Thank you >Paul Finkel >AT&T >732-457-5170 > > -- David Williams Maintainer of the Informix FAQ Primary site (Beta Version) http://www.smooth1.demon.co.uk Official site http://www.iiug.org/techinfo/faq/faq_top.html I see you standin', Standin' on your own, It's such a lonely place for you, For you to be If you need a shoulder, Or if you need a friend, I'll be here standing, Until the bitter end... So don't chastise me Or think I, I mean you harm... All I ever wanted Was for you To know that I care