You can see “WARNING: AQ_TM_PROCESSES is set to 0. System operation might be adversely affected.” warnings at certain intervals in the database alert log file. The reason for these warnings is that the value of the parameter aq_tm_processes is set to 0.
The AQ_TM_PROCESSES parameter must have a value of at least 1. It can be between 0 and 10.
The parameter aq_tm_processes is set to 0 to turn off Queue Monitor Coordinator. Recommended is that no value is assigned to this parameter and the value is automatically assigned. If Oracle Streams is used and the aq_tm_processes parameter is set to 0, it can cause serious problems in the system.
You can set this parameter to be the default value as follows. The database will need to be restarted after the parameter change.
SQL> connect / as sysdba
SQL> alter system reset aq_tm_processes scope=spfile sid='*';
SQL> shutdown immediate;