You can manage parallel statement queuing for multitenant container databases (CDBs) and pluggable databases (PDBs).
To determine the order that queries are dequeued, use the
shares directives in the multitenant container database (CDB) and pluggable database (PDB) resource plans. CDB and PDB resource plans work in a hierarchical fashion. The CDB resource plan selects the PDB whose queries should be scheduled next. That resource plan of that PDB selects the consumer group within the PDB whose queries should be scheduled next.
The maximum parallel servers that a consumer group can use is determined by directives in two plans. In the CDB plan, the
parallel_server_limit directive specifies the percentage of parallel servers that its PDB can use. In the PDB plan, the
parallel_server_limit directive specifies the percentage of parallel servers that the consumer group can use. If both limits are specified, they are multiplied together to get the final percentage.