Parallel Query Downgraded to Serial When CDB Consumer Group is Enabled in 12c
(Doc ID 2048186.1)
Last updated on FEBRUARY 02, 2022
Applies to:Oracle Database Cloud Service - Version N/A and later
Oracle Database - Enterprise Edition - Version 126.96.36.199 to 188.8.131.52 [Release 12.1]
Oracle Database Cloud Schema Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
Parallel query running inside a PDB downgraded to serial
DOP is downgraded to 0 when CDB Consumer Group is enabled and parallel_degree_policy=manual and segment is not in memory.
If the segment is in memory or parallel_degree_policy=adaptive DOP does not get downgraded.
The inconsistent DOP (Degree of Parallelism) when running SQLs with parallel hints when CDB consumer group is enabled.
A snippet of the parallel trace shows that DOP was downgraded to 0 due to 350:
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