How to Multiplex Control Files ?

To multiplex a control file:

1. Set the new location.

   Example: SQL> alter system set control_files='/u01/app/control04.ctl',
                    '/u01/app/control01.ctl','/u01/app/control02.ctl',
                     '/u01/app/control03.ctl' scope=spfile;

2. Shutdown the database
3. Copy a already existing controlfile to the above locatons
   and rename it.

4. Startup the database.

Read more >>

Types of Checkpoints in Oracle.

Checkpoint types can be divided as INCREMENTAL and COMPLETE.

Also COMPLETE CHECKPOINT can be divided further into
PARTIAL and FULL.

In Incremental Checkpoint,checkpoint information is written to the
datafile header and controlfile In the following cases:

Read more >>

Oracle 10g BigFile Tablespace.

One of the new features in oracle 10g is the introduction of 
bigfile tablespace.

A bigfile tablespace is a tablespace which basically consists of one
and only one datafile which can be as large as 128 Terabytes in size
depending upon the block size of the tablespace.

Following is the list of block sizes and maximum
sizes for bigfile tablespaces.

Read more >>

Oracle Database Tablespace Management.

To check for all the tablespaces in your database
issue the following query.

SQL> select tablespace_name from dba_tablespaces;

TABLESPACE_NAME
------------------------------
SYSTEM
SYSAUX
UNDOTBS1
TEMP
USERS
EXAMPLE

6 rows selected.

Read more >>

Oracle Database Read Only Mode.

Opening a database in read only mode

Opening a database in read only mode enables you to 
query an open database. Read only mode guarantees nothing
is written to the datafiles and redo log files.

Read more >>

Oracle Database Startup Restricted Feature.

STARTUP RESTRICTED 

when to use

1. perform import or export of data
2. Data load using sql*loader
3. temporarily prevent users from accessing the data.
4. Migration or upgrade operations.

Read more >>

Oracle 11g RMAN Active Database Duplication Feature.

Earlier in pre Oracle 11g releases in order to clone or duplicate a database, we had to take backups with RMAN of the source database and copy the backup files to the destination server as well. But with 11g database duplication or cloning has gone one step further. With the new RMAN active database duplication feature taking backups and staging them is no longer required. RMAN can now directly clone the database from the source without the need for backups. The only criteria are that the source database should be in archivelog mode.

Read more >>