Re: DS_MAX_QUERIES & DS_TOTAL _MEMORY parameter

These parameters are used by Informix to determine the amount of resource to allocate for a Parallel Database Query (PDQ) DS_MAX_QUERIES - this specifies the maximum number of PDQ that can be execute at any given time. This parameter is quite subjective based on the number of users that you would want to execute PDQ, but remember that your server has a finite number of resources. So limit the number if your server can't handle the load. DS_TOTAL_MEMORY = this specifies the maximum amount of memory that can be used by ALL PDQ queries. Try to specify as much memory as you have without affecting the performance of your OLTP system (if you have any). Or you can set this to a high value provided that users don't execute PDQ during high transaction activity. But usage of these or any PDQ parameters is dependent on two important parameters, these are MAX_PDQPRIORITY and PDQPRIORITY. MAX_PDQPRIORITY - determines the maximum PDQ resources that will be allocated to a user executing a PDQ. This is set within the ONCONFIG file or changed using the onmode utility. PDQPRIORITY - this is set at the session (user) level, which specifies the amount of resources the user would want to execute the PDQ. Based on experience they always specify 100 (all resources). If a user sets PDQPRIORITY to 100 and MAX_PDQPRIORITY is also 100, then only one user can execute PDQ at any given time.So try to control the usage of resources using the MAX_PDQPRIORITY, which might be dependent on the DS_MAX_QUERIES. For example if you expect 5 users to concurrently run PDQ, set MAX_PDQPRIORITY to 20. So that if a user requests PDQPRIORITY is 100, IDS will only allocate 20 percent of the resources. For more detailed information refer to the Informix Performance Guide. You can download it from Informix's web site if you don't have it yet. Don chivaviro1379@my-deja.com wrote: > > How do these parameters affect perfrmance and How Best can you tune > them. > > Sent via Deja.com http://www.deja.com/ > Before you buy.