In Oracle 23ai, a new open mode called Hybrid Read-Only has been introduced for pluggable databases (PDBs). When a PDB is set to this mode, local users can only connect with read-only access. However, common users are not restricted and can still perform write operations.
SQL> ALTER PLUGGABLE DATABASE ORCLORPDB OPEN HYBRID READ ONLY;
Pluggable database altered.
SQL> show pdbs;
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- ------------------------------ ---------- ----------
2 PDB$SEED READ ONLY NO
3 ORCLORPDB READ WRITE NO
Testing Write Access as SYS User
Now, we connect to ORCLORPDB as the SYS user and test write operations:
sqlplus "sys/sys@target:1522/ORCLORPDB as sysdba"
SQL> show user;
USER is "SYS"
SQL> select OPEN_MODE from v$pdbs;
OPEN_MODE
----------
READ WRITE
SQL> create table vahid.tbl1(id number);
Table created.
As seen above, the SYS user sees the OPEN_MODE as READ WRITE, even though the PDB was opened in HYBRID READ ONLY mode.
Testing Write Access as Local User
Now, let’s repeat the test with a local user named VAHID:
sqlplus "vahid/reeyuuy@target:1522/ORCLORPDB"
SQL> show user;
USER is "VAHID"
SQL> select OPEN_MODE from v$pdbs;
OPEN_MODE
----------
READ ONLY
SQL> create table vahid.tbl2(id number);
ORA-16000: Attempting to modify database or pluggable database that is open for read-only access.
As expected, the local user (VAHID) is not allowed to perform write operations.
Checking Hybrid Read-Only Mode Status
Regardless of how users connect to the PDB, the V$CONTAINER_TOPOLOGY view can be used to check whether the PDB is in HYBRID READ ONLY mode:
SQL> select IS_HYBRID_READ_ONLY, CON_NAME, OPEN_MODE from V$CONTAINER_TOPOLOGY;
IS_HYBRID_READ_ONLY CON_NAME OPEN_MODE
-------------------- ---------- ----------
YES ORCLORPDB READ WRITE
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