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Optimizer stats job runs simultaneously only on two PDBs at a time. Check AUTOTASK_MAX_ACTIVE_PDBS which defaults to 2 (Doc ID 3011691.1)

Last updated on JULY 16, 2024

Applies to:

Oracle Database - Enterprise Edition - Version and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Information in this document applies to any platform.


You may have a container database (CDB) with >100 pluggable databases (PDBs).
When running a short statistics job (using the Query Optimizer), the job starts on 2 PDBs and completes (in around a minute) but then takes another 10 minutes to start on the next two PDBs, and then 10 minutes again, so on.

This can be seen in CDB_SCHEDULER_JOB_RUN_DETAILS and the following query:

You cannot seem to start a statistics job on more than 2 PDBs at the same time.
So the cause of the Optimizer Stats jobs not running to completion on ~100 PDBs is the 10 minute delay to the next start in a different PDB.


 You are attempting to run a simple Optimizer Stats collection job on multiple PDBs but see delays and eventual failure on some PDBs


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