Underscore Parameters Set In Pluggable Databases Are Not Persistent After Restart

(Doc ID 2335758.1)

Last updated on DECEMBER 14, 2017

Applies to:

Oracle Database - Enterprise Edition - Version 12.1.0.2 to 12.1.0.2 [Release 12.1]
Information in this document applies to any platform.

Symptoms

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

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