Hello
All underscore parameters which are set on a PDB level are ignored during database start.
An underscore parameter is set on a PDB level in memory and spfile. After restarting database the parameter is still in pfile but not anymore in memory.
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- ------------------------------ ---------- ----------
2 PDB$SEED READ ONLY NO
3 Q00A READ WRITE NO
SQL> alter session set container=Q00A;
SQL> alter system set -_push_join_union_view-=FALSE scope=both sid='*';
SQL> show parameter -_push_join_union_view-
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
_push_join_union_view boolean FALSE
SQL> show spparameter -_push_join_union_view-
SID NAME TYPE VALUE
-------- ----------------------------- ----------- ----------------------------
* _push_join_union_view boolean FALSE
srvctl stop db -d cdbq00r; srvctl start db -d cdbq00r
SQL> show parameter -_push_join_union_view-
no rows
SQL> show spparameter -_push_join_union_view-
SID NAME TYPE VALUE
-------- ----------------------------- ----------- ----------------------------
* _push_join_union_view boolean FALSE
Thanks
Venkat