MAX_PDQPRIORITY

onconfig.std
value

100

if not present

100

range of values

0 through 100

takes effect

On all user sessions

utilities

onutil

refer to

Your IBM Informix: Performance Guide

MAX_PDQPRIORITY limits the PDQ resources that the database server can allocate to any one DSS query. MAX_PDQPRIORITY is a factor that is used to scale the value of PDQ priority set by users. For example, suppose that the database administrator sets MAX_PDQPRIORITY to 80. If a user sets the PDQPRIORITY environment variable to 50 and then issues a query, the database server silently processes the query with a PDQ priority of 40.

In Extended Parallel Server, PDQPRIORITY affects only memory resources. The values of the MAX_PDQPRIORITY and PDQPRIORITY parameters do not affect parallel operations. Parallel operations (such as scans, sorts, and joins) can occur if multiple coservers and CPU VPs are involved in the operation and the default memory is sufficient for parallel threads. For more information on parallel operations, refer to your IBM Informix: Performance Guide.

You can set MAX_PDQPRIORITY to one of the following values.

Value

Database Server Action

100

Uses all available memory for processing queries in parallel.

number

Sets the percentage of the user-requested PDQ resources actually allocated to the query. The number variable is an integer between 0 and 100.

To modify the MAX_PDQPRIORITY parameter dynamically, use the onutil SET command. Example:

% onutil
1> SET MAX_PDQPRIORITY 50;