Overriding PDQPRIORITY Settings

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Overriding PDQPRIORITY Settings

The PDQPRIORITY setting determines how much of the amount of the memory set aside for DSS queries an individual query requests. For information about how the database server uses PDQPRIORITY to manage memory allocation for queries, see How the RGM Grants Memory.

Tip:

You can bypass the PDQPRIORITY setting entirely, and allow the database server to allocate an amount of memory that is appropriate for each query. To determine the amount of memory to allocate, the optimizer analyses the query SQL statements and the data distribution statistics for the tables that the query accesses. For automatic memory allocation, however, current statistics are critically important. For information, see Enabling Optimizer-Determined Memory Allocation.

Although you can set PDQPRIORITY as a global configuration parameter, client applications or users can override the global PDQPRIORITY setting in the following ways:

With the PDQPRIORITY environment variable
The UNIX syntax for the PDQPRIORITY environment variable is as follows:
```
>>-export--PDQPRIORITY--=--'--lowval--+------------+--'--------><
                                      '-,--highval-'
```
When PDQPRIORITY is set in the environment of a client application, it specifies the percentage of shared memory that can be allocated to any query that client starts.
From a client program that uses the SET PDQPRIORITY statement
The syntax of the SET PDQPRIORITY statement is as follows:
```
>>-SET--PDQPRIORITY--LOW--lowval--HIGH--highval--;-------------><
```
The values that the SET PDQPRIORITY statement specify take precedence over the setting of the PDQPRIORITY environment variable or the PDQPRIORITY configuration parameter. The setting of MAX_PDQPRIORITY limits the actual percentage of resources granted, as described in Limiting the Amount of Memory That a Query Actually Receives.