CURRENT QUERY ACCEL field (QUERY_ACCELERATION subsystem parameter)
The QUERY_ACCELERATION subsystem parameter determines the default value that is to be used for the CURRENT QUERY ACCELERATION special register.
The QUERY_ACCELERATION subsystem parameter is used when no value is explicitly set for the CURRENT QUERY ACCELERATION special register by the SQL statement SET CURRENT QUERY ACCELERATION.
| Acceptable values: | 1, 2, 3, 4, 5 |
|---|---|
| Default: | 1 |
| Update: | option 31 on panel DSNTIPB |
| DSNZPxxx: | DSN6SPRM.QUERY_ACCELERATION |
- 1 (NONE)
- Specifies that no query acceleration is done.
- 2 (ENABLE)
- Specifies that queries are accelerated only if Db2 determines that it is advantageous to do so. If there is an accelerator failure while a query is running, or the accelerator returns an error, Db2 returns a negative SQLCODE to the application.
- 3 (ENABLE_WITH_FAILBACK)
- Specifies that queries are accelerated only if Db2 determines that it is advantageous to do so. If the accelerator returns an error during the PREPARE or first OPEN for the query, Db2 executes the query without the accelerator. If the accelerator returns an error during a FETCH or a subsequent OPEN, Db2 returns the error to the user, and does not execute the query.Restriction: If the query contains a passthrough-only expression, Db2 returns an error and does not accelerate the query, even if a matching user-defined function exists. For more information about passthrough-only expressions, see Accelerating queries with passthrough-only expressions.
- 4 (ELIGIBLE)
- Specifies that queries are accelerated if they are eligible for acceleration. Db2 does not use cost information to determine whether to accelerate the queries. Queries that are not eligible for acceleration are executed by Db2. If there is an accelerator failure while a query is running, or the accelerator returns an error, Db2 returns a negative SQLCODE to the application.
- 5 (ALL)
- Specifies that queries are accelerated if they are eligible for acceleration. Db2 does not use cost information to determine whether to accelerate the queries. Queries that are not eligible for acceleration are not executed by Db2, and an SQL error is returned. If there is an accelerator failure while a query is running, or the accelerator returns an error, Db2 returns a negative SQLCODE to the application.