Underscore Parameters Set In Pluggable Databases Are Not Persistent After Restart (Doc ID 2335758.1)

Last updated on MARCH 18, 2022

Applies to:

Symptoms

• Underscore parameters set in pluggable databases are not persistent after the database restart.
  
  Example:
  Parameter _optimizer_use_feedback=FALSE is applied to a single PDB within a 12c container:
  
  SQL> alter session set container = PDB1;
  SQL> alter system set "_optimizer_use_feedback"=FALSE scope=BOTH;
• After restart the parameter is no longer applied, the following commands do not return anything:
  
  SQL> show parameter "_optimizer_use_feedback"
  SQL> show parameter _optimizer_use_feedback

The parameter _optimizer_use_feedback=FALSE applied on 12c PDB not persistent after restart.
Similarly, there are other underscore (Optimizer related and other) parameters that are set but not persistent after database restart.
As the parameters are not set persistently in PDBs, there are suboptimal execution plan for the SQL statements in PDBs upon database restart.

Changes

 Upgrade to 12c multitenant environment (CDB/PDB).

Cause

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.