Re: DS_TOTAL_MEMORY & performance questions

sujata_soman_at_omm-la2-infotech-001@internet.omm.com wrote: > > Question. > Does the setting of DS_TOTAL_MEMORY affect ALL queries, or only > queries running as a PDQ ( with the pdqpriority explicitly set for that > session ). Only DSS queries (PDQPRIORITY set). > Also, > if I have a very large query, and my DS_TOTAL_MEMORY has been set to > something > lower than what the query needs, what happens to it. Does it just die > or wait ( for what ? ) Wait (for DSS memory). Remember DS_TOTAL_MEMORY is apportioned using both PDQPRIORITY _and_ MAXPDQPRIORITY. > If the performance of my large query is pathetically slow, how do > I link it > to DS_TOTAL_MEMORY ? Actually, how do I find out the bottleneck ? You really need to check out the manuals or go on the system administration course, where all this is explained in excruciating detail. :-) Essentially your PDQPRIORITY setting together with your MAXPDQPRIORITY value are used to allocate DSS resources to your query. You can monitor ALL this with: onstat -g mgm And I'm not going into detail on the output, because there are pages. ;-) But check for blocked queries. The most common mistake made is that a DSS query will run immediately. If there are no resources left, it will wait until there are. This means it is possible for your query to spend most of it's life "waiting" instead of "running", hence giving you the impression of a slow query. 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"!|/ ////////| +----------------------+-----------------------------------+-----------+