OPEN STANDBY DATABASE IN READ ONLY

SQL> select PROTECTION_MODE,PROTECTION_LEVEL FROM V$DATABASE;

PROTECTION_MODE      PROTECTION_LEVEL
-------------------- --------------------
MAXIMUM PERFORMANCE  MAXIMUM PERFORMANCE

SQL> select name,db_unique_name,open_mode,DATABASE_ROLE from v$database;

NAME  DB_UNIQUE_NAME OPEN_MODE      DATABASE_ROLE
--------- ------------------------------ -------------------- ----------------
ORCL  ORCLSTB1 MOUNTED      PHYSICAL STANDBY

 SQL> alter database open read only;

Database altered.

SQL> select name,db_unique_name,open_mode,DATABASE_ROLE from v$database;

NAME  DB_UNIQUE_NAME OPEN_MODE      DATABASE_ROLE
--------- ------------------------------ -------------------- ----------------
ORCL  ORCLSTB1 READ ONLY      PHYSICAL STANDBY


SQL> select PROTECTION_MODE,PROTECTION_LEVEL FROM V$DATABASE;

PROTECTION_MODE      PROTECTION_LEVEL
-------------------- --------------------
MAXIMUM AVAILABILITY MAXIMUM AVAILABILITY


SQL> SELECT database_role, open_mode FROM v$database;

DATABASE_ROLE OPEN_MODE
---------------- --------------------
PHYSICAL STANDBY READ ONLY WITH APPLY