Performance system values: Allow background database statistics collection
The Allow background database statistics collection system value is also known as QDBFSTCCOL. You can use this system value to specify the types of requests for database file statistics collection that are allowed to be processed by the system job QDBFSTCCOL.
| Quick reference | |
|---|---|
| Location | From IBM® Navigator for i, select . Right-click on Performance and click Properties, then select the Database tab. |
| Special authority | None. |
| Default value | Allow user-created and system-generated database statistics. |
| Changes take effect | Immediately. |
| Lockable | No. |
What can I do with this system value?
You can specify the types of requests for database file statistics collection that are allowed to be processed by system job QDBFSTCCOL. However, this system value does not affect statistical collections that are requested either by a user or automatically by the database manager to be processed in the foreground.
The creator of a database file statistics collection request can specify either immediate or background processing. When immediate is specified, the statistics collection will be performed within the requester's process and control is not returned until the statistics collection is complete. The processing of immediate statistics collection requests are not affected by the setting of this system value. However, when background is specified, the request is queued to system job, QDBFSTCCOL, and control is returned immediately to the requesting process.
System job, QDBFSTCCOL, can select to process requests from either user-created requests, system-generated requests, or both based on the value of this system value. Requests which are not selected will remain queued until either the system job is ready to process the request or the system value is changed to allow requests of that type to be processed.
When this system value is changed to a more restricted value, the processing of statistic collection requests in progress in the statistics system job, that are not allowed at the new value, is ended. Their processing is restarted when this system value is changed back to a value that allows their processing.
From the following types of requests, you can select one type, both types (*ALL), or neither (*NONE):
- User-created requests (*USER)
- This indicates that user requested database file statistics collections are allowed to be processed by the database statistics system job.
- System-generated requests (*SYSTEM)
- This indicates that system-generated database file statistics collections are allowed to be processed by the database statistics system job.