Oracle – Multitenant – Create a sysdba Common User

😎 To create a sysdba user that can administrate all containers:

sys@ORCL> show con_id

CON_ID
------------------------------
1
sys@ORCL> show con_name

CON_NAME
------------------------------
CDB$ROOT
 
sys@ORCL> create user c##username identified by <password>;

User created.

sys@ORCL> grant create session to c##username;

Grant succeeded.

sys@ORCL> grant sysdba to c##username container = ALL;

Grant succeeded.

If it is necessary to change the common user prefix (or get rid of it!), the value of _common_user_prefix_common_user_prefix can be changed:
sys@ORCL> select rpad(ksppinm,40) ||' ---->  '||ksppstvl "param, value" from x$ksppi a,x$ksppsv b
  2  where a.indx=b.indx and substr(ksppinm,1,1) = '_' and ksppinm like '%common%';

param, value
_ksipc_common_sl                         ---->
_eliminate_common_subexpr                ---->  TRUE
_dump_common_subexpressions              ---->  FALSE
_common_data_view_enabled                ---->  TRUE
_common_user_prefix                      ---->  C##