Re: Update statistic question

Susan Elliott (ISG) wrote: > > Thanks to all of those who have been answering my questions over the > last few days !!! Its much appreciated !!! > > I have a question about the Update statistics script that we do > here.... > > #### Beginning of script ##### > set isolation dirty read; > update statistics medium distributions only; > update statistics high for table (Table name) (Column Name)> distributions only; > {We do the update statistics high on 13635 tables, like above} > update statistics low;> ##### End of script ###### > > This was set up for me. I have worked out that the high over writes > the mediums on the tables/ columns specified. It does an update low > across the whole database. Correct. > Does this mean that the lows have over written the highs ??? No. Low, medium, high is misleading, in that a low has nothing to do with distributions, whereas both medium and high write distribution information. > Should I change the order of this to low, med and then to the highs ?? > Or to med, low and then the highs ?? Makes no difference where you put the low in this case. > My next stumbling block is the above script runs sequentially and > takes over 2 days to complete. (we don't run it very often now) So > that we can run this more often..... and maybe we will get better > performance... Yes... > What are my options in breaking up the above script ???? Depends on available resources. > What do other folk do ??? Break it up based on available resources. :-) > Can I just break the highs script up and run several at once ??? Yes. > Can split it up into table types... general ledger, accounts payable, > sales etc and do the low, med and then the high on each table types > ??? I would rather look at table location and split it up per disk. > How many scripts I run at once ??? What is this dependant on ??? Depends on available resources. Available resources. :-) Start with 2 or 3 updates per CPU. > physical cpus ? cpu vps ?? Yes. Yes. Make sure you have lots of temp dbspace. Set PSORT_NPROCS & PDQPRIORITY. Do NOT set DBUPSPACE. Hope that helps, -- Mark. +----------------------------------------------------------+-----------+ |Mark D. Stock - Informix SA http://www.informix.com |//////// /| |mailto:mdstock@informix.com FAQ http://www.iiug.org |///// / //| | +-----------------------------------+//// / ///| | Tel: +27 11 807 0313 |If it's slow, the users complain. |/// / ////| | Fax: +27 11 807 2594 |If it's fast, the users keep quiet.|// / /////| |Cell: +27 83 250 2325 |Therefore, "No news: travels fast"!|/ ////////| +----------------------+-----------------------------------+-----------+