IBM Cognos BI supports batch processing for a variety of tasks and objects. A common example would be a scheduled job containing report executions.
The monitor service stores the job and report execution commands in a Task Queue. Commands on the task queue are run as the system has capacity to do so.
There is a balance to be struck between the Cognos installation size and the rate at which background processing occurs, or put another way your installation hardware will have a maximum capacity for background processing that you cannot exceed.
You will notice that if your scheduled execution rate exceeds your system capacity then the Task Queue will start to fill up. If you open the current activities view in Cognos Administration, it will have many Pending report executions.
Stopping the scheduled activities using the upcoming activities view is one way to solve this issue and let the backlog of report be processed.
Another way that some customers have chosen to use is NC_DROP. This involves dropping all of the tables in the notification database that are prefixed NC_ When the system restarts, the tables are rebuilt and repopulated.
This has the drawback however that all of the schedules are re-synchronized to the NC tables which can take some hours on a big system.
A recommended alternative is to stop the server and use the following SQL script to truncate the task queue tables. The schedule data in the NC tables is left alone but the current activities view is now empty on restart. Beware that report executions that were pending will not now execute.
TRUNCATE TABLE NC_TASK_HISTORY_DETAIL;
TRUNCATE TABLE NC_TASK_PROPERTY;
TRUNCATE TABLE NC_TASK_QUEUE;
TRUNCATE TABLE NC_TSE_STATE_MAP;
sql script for current activity queue truncation in cognos 10