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Table 23 summarizes
the configuration parameters, environment variables, and the SQL statement
that control how the database server allocates resources to PDQ in Extended Parallel Server.
The value set by the SQL statement supersedes values
set by the environment variables, and values set by environment
variables supersede values set by configuration parameters.
Table 23. Parameters Used for Controlling PDQ in Extended Parallel Server
Configuration
Parameters |
Environment
Variables |
SQL
Statements |
Purpose of Parameter |
| DS_ADM_POLICY |
|
|
Indicate policy that RGM should use to schedule
queries. |
| DS_MAX_QUERIES |
|
|
Maximum number of PDQ queries that can be active
at any one time |
| MAX_PDQPRIORITY |
|
|
Percentage of user's requested PDQPRIORITY
value that the database server grants |
| OPTCOMPIND |
OPTCOMPIND |
|
Indicate a preferred join type to the query optimizer |
| PDQPRIORITY |
PDQPRIORITY |
SET PDQPRIORITY |
Request minimum and maximum percentage of PDQ
memory for an application or a specific query |
|
|
SET SCHEDULE LEVEL |
Request scheduling priority for an application
or a specific query |
Each PDQ configuration parameter shown above can be modified
on the fly using the onutil SET command.
For more information on the PDQ parameters,
refer to the chapter on configuration parameters in the IBM Informix: Administrator's Reference and to your IBM Informix: Performance Guide.
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