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

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.

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

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.

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.

It would mean that when sync operation of pluggable database was performed while opening it, there was some error and synchronization was not able to complete successfully. Pluggable database would be open, but it will be in restricted mode (as you will see in bellow example). In this case, we should immediately query PDB_PLUG_IN_VIOLATIONS to see what has gone wrong.

ORA-00214: control file version inconsistent with file

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.

ORA-00214: control file 'D:\ORACLE\ORADATA\PRODDB\CONTROL02.CTL'
version
857358007 inconsistent with file 'G:\ORACLE\ORADATA\PRODDB\CONTROL01.CTL'
version 857358000

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)

Tablespace Growth History and Forecast for 12c and Above

Finding space usage of tablespaces and database is what many DBAs want to find. In this article I will explain how to find out space usage history and forecasting future growth of tablespaces. For 10g, 11g, you can use Tablespace Growth History and Forecast (10g, 11g) and Database Growth History and Forecast (10g, 11g) scripts.

For 12c container/pluggable Database Growth History and Forecast, see script Database Growth History and Forecast (12c and Above). 

Database Growth History and Forecast for 12c and Above

For 10g, 11g, you can use Tablespace Growth History and Forecast for 10g and 11g and Database Growth History and Forecast for 10g and 11g) scripts.
For 12c and above tablespace growth history and forecast, you can use Tablespace Growth History and Forecast for 12c and Above script.