RE: update statistics concurrency with application SQL

There is a performance impact on update statistics because it reading rows in tables and updating systables and sysdistrib. If one of you sql queries (programs) tries to search on a table using the column that update statistics is rebuilding at that exact time, then the program will get a "invalid distribution format ..." error message (not sure of the exact text) and will die. The answer is to try to run update statistics at a low time. (We update stats nightly). The following assumes there are normally patterns of activity when volatile tables are less likely to be used. There are several alternatives: 1. Update stats of tables after the data in then is added/deleted/altered. Other tables schedule at a low use time. 2. Update stats at a time when specific tables are not normally in use. Murray Wood -----Original Message----- From: owner-informix-list@iiug.org [mailto:owner-informix-list@iiug.org]On Behalf Of roswil@my-deja.com Sent: Wednesday, February 09, 2000 6:14 AM To: informix-list@iiug.org Subject: Re: update statistics concurrency with application SQL In article <85ge56$se5$1@nnrp1.deja.com>, roswil@my-deja.com wrote: > Is there any real or serious problem with running update statistics > concurrent with application's SQL ? Does locking occur that severely > impacts contention between update statistics and application's SQL ? > Is there any known case/experience of table corruption due to running > update statistics while application's SQL are running concurrently ?> Are there specific configuration setting to check or revise in order to > run update statistics and application's SQL concurrently ? We make > extensive use of referential integrity - is/should this be a factor in > any way ? > Does anyone have comparisons of duration to run update statistics by > itself versus running it under a light, medium and heavy work load ? > > We are running a 56GB instance using IDS 7.30UC8, HPUX 11.0. We run > update statistics in database exclusive mode every two weeks on about> 150 tables. We first drop all distributions table by table and > re-create the distributions as Informix recommends. > I appreciate your help. > Anyone ? thanks Sent via Deja.com http://www.deja.com/ Before you buy.