Tuesday, July 28, 2015

Checkpoint not Complete

This is one of the most common messages a DBA could see in alert log file of a database. Exact message should be similar to the following
Wed Mar 04 12:02:01 2015
Thread 1 cannot allocate new log, sequence 201
Checkpoint not complete

Thursday, July 23, 2015

Finding Sessions with High CPU Usage

If database server CPU usage is showing 100%, or high 90%, DBA needs to find out which session is hogging the CPU(s) and take appropriate action. I will explain in the following that how can we find out the session(s) which are excessively using CPU.

Monday, July 20, 2015

ORA-03135: connection lost contact

This error may be accompanied by ORA-03113: end-of-file on communication channel. This actually means that your session has been dropped and there could be different reasons which might have caused this. Most commonly; a firewall between client and server could have caused this session/connection drop, if firewall senses some session to

Wednesday, July 15, 2015

Testing RMAN Restore

Starting 10g, we can test our backups whether backups are valid and can be used for a successful restore/recovery of the database or not. We can do so by using “RESTORE VALIDATE” command from RMAN. RESTORE VALIDATE command would simulate a restore of the backups by reading backup pieces. If it completes successfully, it would mean that backup is good and can be used for restoration and recovery of database in case of media failure or a disaster.

Sunday, July 12, 2015

Warning: PDB altered with errors and PDB_PLUG_IN_VIOLATIONS

If you open your pluggable database and you receive following warning,
SQL> alter pluggable database pdb2 open;

Warning: PDB altered with errors.

Wednesday, July 8, 2015

ORA-00214: control file 'string' version string inconsistent with file 'string' version string

If there is a server crash, there could be a possibility that you see ORA-00214 error; once server is up again, and you try to start (mount) the database. Error could be similar to the following.


Monday, July 6, 2015

CDB_TABLESPACES not Showing Tablespaces of Pluggable Database

Starting 12c, along with DBA_*, ALL_* and USER_* views, there is another time of data dictionary views available which are CDB_* views. For example, along with DBA_TABLESPACES view there is also CDB_TABLESPACES view. These CDB_* views in a container database show all information of all containers (container + all pluggable databases)