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.

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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:

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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.

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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.

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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.

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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.

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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.

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Oracle 11g I/O Calibration Feature.

Earlier in order to assess the I/O capabilities of the system
on which you would install Oracle database, there were
two options.

1)Use third party tools (Mercury loadRunner, Benchmark Factory etc).
2)Use ORION from Oracle.

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Oracle 11gR2 Deinstall tool.

Before 11gR2 Uninstalling the Oracle software was really
a pain both on windows as well as on linux platforms.

But now Oracle 11gR2 with comes with aa awesome tool 'Oracle Deinstall utiliy'.

Just execute one simple command answer a couple of questions
and you can remove your whole Oracle software along with your database
and listeners.

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Oracle 11g create spfile from memory.

In pre Oracle 11g releases we had the feature of conversion from SPFILE to PFILE and vice versa. But Oracle 11g has gone one step further, SPFILE can now be created directly from memory.

SQL> create spfile=’/u01/app/spfileorcl.bak’ from memory;

This command will capture all the settings from the memory and dump them to an SPFILE. This is a very useful utility to take backup of your SPFILE before any changes are made using ‘alter system’ command. In order to check and read the new created file the following command can be used : -

 
SQL>!strings /u01/app/spfileorcl.bak

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Oracle 11g Memory Advisor feature.

Among many dynamic views oracle has added a new view,
V$MEMORY_TARGET_ADVICE. The purpose of this view is 
to give recommendations related to the 
sizing of the memory_target parameter.

Before going further please make sure that memory
management is set to automatic in your database,
otherwise this feature will not work.

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