# [26ai] Hybrid Read-Only Mode PDB

*If you prefer to read in Spanish* [***Spanish version***](https://dbaenlasombra.com/26ai-hybrid-read-only-mode-pdb)*.*

Today, let's talk about a new ***Hybrid Read-Only*** open-mode in 26ai.

When we set up this mode, our PDB is **read-only** mode for ***local users*** and **read-write** for **common users**.

So, let's get down to business!

First of all, let's create a new PDB:

```sql
SQL> CREATE PLUGGABLE DATABASE PDB_HYBRID ADMIN USER admin IDENTIFIED BY admin keystore identified by external store;

Pluggable database created.

SQL> ALTER PLUGGABLE DATABASE  PDB_HYBRID OPEN;
Pluggable database altered.

SQL> ALTER PLUGGABLE DATABASE  PDB_HYBRID SAVE STATE;
Pluggable database altered.
```

Let's create both users:

```sql
SQL> CREATE USER c##hybrid IDENTIFIED BY "XXXXXXX";
User created.
SQL> GRANT DBA TO c##hybrid CONTAINER=ALL;
Grant succeeded.

SQL> alter session set container=pdb_hybrid;
SQL> create smallfile tablespace tb1 
      datafile size 1m autoextend on maxsize 10m;

Tablespace created.

SQL> CREATE USER hybrid IDENTIFIED BY "XXXXXXX"
  DEFAULT TABLESPACE tb1
  TEMPORARY TABLESPACE temp
  QUOTA UNLIMITED ON tb1;  

User created.

SQL> GRANT DBA TO hybrid;

Grant succeeded.
```

All right, we have just created both users, on one hand, the **common user** is ***c##hybrid***. On the other hand, the **local user** is ***hybrid*** .

Before opening it with the new state, let's connect as **local user** in order to create a table with some information:

```sql
SQL> conn hybrid/"XXXXX"@X.X.X.X:1521/pdb_hybrid.XXXX.XXXX.XXXX.com
Connected.
SQL>      
SQL> 
 Create table T_TEST AS 
  SELECT OBJECT_NAME FROM ALL_OBJECTS;

Table created.
```

Let's connect to **CDB$Root** in order to open the PDB in **hybrid read-only** mode.

```sql
SQL> alter pluggable database PDB_HYBRID close;

Pluggable database altered.

SQL> alter pluggable database PDB_HYBRID open hybrid read only;

Pluggable database altered.

SQL> r
    select con_name,
           open_mode,
           is_hybrid_read_only
    from   v$container_topology

CON_NAME             OPEN_MODE  IS_HYBRID_READ_ONLY
-------------------- ---------- --------------------
CDB$ROOT             READ WRITE NO
PDB$SEED             READ ONLY  NO
PDB_HYBRID           READ WRITE YES
```

Let's connect as **local user** in order to execute *DML* (delete) and *DDL* (truncate).

```sql
SQL>  conn hybrid/"XXXXX"@X.X.X.X:1521/pdb_hybrid.XXXX.XXXX.XXXX.com
Connected.
SQL> set linesize 1000
SQL> col name format a20
SQL> select name, open_mode from v$pdbs;

NAME                 OPEN_MODE
-------------------- ----------
PDB_HYBRID           READ ONLY

SQL> delete T_TEST;
delete T_TEST
       *
ERROR at line 1:
ORA-16000: Attempting to modify database or pluggable database that is open for read-only access.
Help: https://docs.oracle.com/error-help/db/ora-16000/


SQL> truncate table T_TEST;
truncate table T_TEST
*
ERROR at line 1:
ORA-16000: Attempting to modify database or pluggable database that is open for read-only access.
Help: https://docs.oracle.com/error-help/db/ora-16000/
```

Both operations failed with the following message "*ORA-16000: Attempting to modify database or pluggable database that is open for read-only access*"

Let's connect as the common user in order to performn the same operations.

```sql
SQL>  conn c##hybrid/"FJA_2026_Oracle19c" 
Connected.

SQL>  alter session set container=PDB_HYBRID;
Session altered.

SQL>  select name, open_mode from v$pdbs;

NAME                 OPEN_MODE
-------------------- ----------
PDB_HYBRID           READ WRITE

SQL> delete hybrid.T_TEST;

52165 rows deleted.

SQL> truncate table hybrid.T_TEST;

Table truncated.

```

Both operations completed sucessfully.

Before calling it a day, when we check **v$pdbs** as local user, the value in OPEN\_MODE is READ ONLY, whereas, the value for common user is READ WRITE.

Looking forward to seeing you in the next article :)