dostats for big big tables

Hi all, running dostats -d -e , I've realized that for the key columns the script runs update statistics low before running update statistics high. Is there anyparticular reason? is it to clean the distributions? My concern is because my system has really big tables and the whole process takes a lot of time. If those big tables have a small daily percent of new rows if you compare with the size of the table, does it worth to run update stats low and then update stats high for the key columns? thanks in advance

If there are a small percentage of new rows and updates, then it's probably not even necessary to run dostats daily. At least not a full run. Look at the -a/-A and -b/-B options. You can use that to only update tables that have had significant percentile changes in the number of rows (-b) or whose stats are too many days old (-a). As to the LOW, it's being run on each full index key to update the sysindices/sysindexes record for that key. Since neither the HIGH nor the MEDIUM contain the entire key for most multi-key indexes that record is not updated by the HIGH or MEDIUM. Therefore, I run the LOW on each of the full keys, then HIGH with DISTRIBUTIONS ONLY so that it does not redundantly update the syscolumns records for the lead columns (the LOW will have done that already). It is therefore needed. Art S. Kagel Oninit (www.oninit.com) IIUG Board of Directors (art@iiug.org) Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on my employer, Oninit, the IIUG, nor any other organization with which I am associated either explicitly or implicitly. Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves. On Thu, Oct 1, 2009 at 5:50 AM, CLAUDIO NAVARRO <claudio.oami@gmail.com>wrote: > Hi all, > > running dostats -d -e , I've realized that for the key columns the script > runs > update statistics low before running update statistics high. Is there any> particular reason? is it to clean the distributions? > My concern is because my system has really big tables and the whole process > takes a lot of time. If those big tables have a small daily percent of new > rows if you compare with the size of the table, does it worth to run update > stats low and then update stats high for the key columns? > > thanks in advance > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > --0015174736527ada910474e113ea