Oracle Undo Tablespace Advisor(DBMS_UNDO_ADV).

As per Doc ID 1580225.1
The package DBMS_UNDO_ADV is undocumented, and it is used internally by the Undo Advisor .

dbms_undo_adv package gives advise based on historical information present in memory or Automatic Workload
Repository. The default retention of AWR is 7 days.

Function longest_query : Returns the length of the longest query for a given period .

Method 1

SELECT dbms_undo_adv.longest_query LONGEST_QUERY FROM dual;

 
Method 2 (using Start/End time)

SELECT dbms_undo_adv.longest_query(SYSDATE-1/24, SYSDATE) LONGEST_QUERY FROM dual;

 
Method 3 (using Begin/End AWR snapshot id)

SELECT dbms_undo_adv.longest_query(345, 768) LONGEST_QUERY FROM dual;


Function required_retention: returns the undo_retention value required for running the longest query.

Method 1

select dbms_undo_adv.required_retention from dual;

Method 2 (using Start/End time)

SELECT Ddbms_undo_adv.required_retention(SYSDATE-1/24, SYSDATE) required_retention FROM dual;

Method 3 (using Begin/End AWR snapshot id)

SELECT dbms_undo_adv.longest_query(345, 768) LONGEST_QUERY FROM dual;



Function best_possible_retention: Returns the best possible undo retention which the current 
undo tablespace can support.

Note:If undo tablespace autoextensible then "maxsize" setting will be taken into account to
 calculate best_possible_retention.


Method 1

SELECT dbms_undo_adv.best_possible_retention best_retention FROM dual;

Method 2 (using Start/End time)

SELECT dbms_undo_adv.best_possible_retention(SYSDATE-1/24, SYSDATE) best_retention FROM dual;

Method 3 (using Begin/End AWR snapshot id)

SELECT dbms_undo_adv.best_possible_retention(345, 768) best_retention FROM dual; 


Function required_undo_size: Returne the appropriate undo tablespace size to satisfy undo retention value.

Method 1

SELECT dbms_undo_adv.required_undo_size(900) required_undo_size FROM dual;

Method 2 (using Start/End time)

SELECT dbms_undo_adv.required_undo_size(900,SYSDATE-1/24, SYSDATE) required_undo_size FROM dual;

Method 3 (using Begin/End AWR snapshot id)

SELECT dbms_undo_adv.required_undo_size(900, 345, 768) required_undo_size FROM dual;

Read more >>

How To Find Views And What Information They Provide In Oracle Database ?

SQL> desc dba_views;
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 OWNER                                     NOT NULL VARCHAR2(30)
 VIEW_NAME                                 NOT NULL VARCHAR2(30)
 TEXT_LENGTH                                        NUMBER
 TEXT                                               LONG
 TYPE_TEXT_LENGTH                                   NUMBER
 TYPE_TEXT                                          VARCHAR2(4000)
 OID_TEXT_LENGTH                                    NUMBER
 OID_TEXT                                           VARCHAR2(4000)
 VIEW_TYPE_OWNER                                    VARCHAR2(30)
 VIEW_TYPE                                          VARCHAR2(30)
 SUPERVIEW_NAME                                     VARCHAR2(30)
 EDITIONING_VIEW                                    VARCHAR2(1)
 READ_ONLY                                          VARCHAR2(1)


SQL> select view_name from dba_views where view_name like'%ROLE%';


VIEW_NAME
------------------------------
V$XS_SESSION_ROLE
DBA_APPLICATION_ROLES
USER_APPLICATION_ROLES
EXU9NTAROLE
EXU81APPROLE
DBA_ROLES
DBA_ROLE_PRIVS
USER_ROLE_PRIVS
ROLE_ROLE_PRIVS
ROLE_SYS_PRIVS
ROLE_TAB_PRIVS

VIEW_NAME
------------------------------
EXU10NTAROLE
SESSION_ROLES
XS_SESSION_ROLES
DBA_SCHEDULER_JOB_ROLES
KU$_DEFROLE_LIST_VIEW
KU$_DEFROLE_VIEW
KU$_DUMMY_ROLE_VIEW
KU$_PROXY_ROLE_LIST_VIEW
KU$_ROLE_VIEW
DBA_CONNECT_ROLE_GRANTEES
PROXY_ROLES

VIEW_NAME
------------------------------
PROXY_USERS_AND_ROLES
ROLE_WM_PRIVS
MGMT$ESA_DBA_ROLE_REPORT

25 rows selected.


SQL> desc dict;
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 TABLE_NAME                                         VARCHAR2(30)
 COMMENTS                                           VARCHAR2(4000)


SQL> select * from dict where table_name like '%ROLE%';

TABLE_NAME
------------------------------
COMMENTS
--------------------------------------------------------------------------------
DBA_ROLES
All Roles which exist in the database

DBA_ROLE_PRIVS
Roles granted to users and roles

USER_ROLE_PRIVS
Roles granted to current user


TABLE_NAME
------------------------------
COMMENTS
--------------------------------------------------------------------------------
DBA_SCHEDULER_JOB_ROLES
All scheduler jobs in the database by database role

DBA_CONNECT_ROLE_GRANTEES
Information regarding which users are granted CONNECT

ROLE_ROLE_PRIVS
Roles which are granted to roles


TABLE_NAME
------------------------------
COMMENTS
--------------------------------------------------------------------------------
ROLE_SYS_PRIVS
System privileges granted to roles

ROLE_TAB_PRIVS
Table privileges granted to roles

SESSION_ROLES
Roles which the user currently has enabled.


9 rows selected.

Read more >>

Create a System Trigger to Enable SQL TRACE for a session..

The following script will enable session trace for the user scott.

[oracle@canada u01]$ cat trace_trigger.sql
set echo on

spool trace_trigger.log

DROP TRIGGER SYS.trace_trigger;

CREATE OR REPLACE TRIGGER sys.trace_trigger
After logon on database
Begin
            if ( user='SCOTT') then
                execute immediate 'alter session set sql_trace=true';
                execute immediate 'alter session set timed_statistics=true';
                execute immediate 'alter session set tracefile_identifier="SCOTT"';
                execute immediate 'alter session set max_dump_file_size=unlimited';
                execute immediate 'alter session set events ''10046 trace name context forever, level 12''';
            End if;
End;
/

spool off;


[oracle@canada u01]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Tue Oct 22 06:04:31 2013

Copyright (c) 1982, 2009, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> @trace_trigger.sql
SQL>
SQL> spool trace_trigger.log
SQL>
SQL> DROP TRIGGER SYS.trace_trigger;
DROP TRIGGER SYS.trace_trigger
*
ERROR at line 1:
ORA-04080: trigger 'trace_trigger' does not exist


SQL>
SQL> CREATE OR REPLACE TRIGGER sys.trace_trigger
  2  After logon on database
  3  Begin
  4              if ( user='SCOTT') then
  5                  execute immediate 'alter session set sql_trace=true';
  6                  execute immediate 'alter session set timed_statistics=true';
  7                  execute immediate 'alter session set tracefile_identifier="SCOTT"';
  8                  execute immediate 'alter session set max_dump_file_size=unlimited';
  9                  execute immediate 'alter session set events ''10046 trace name context forever, level 12''';
 10              End if;
 11  End;
 12  /

Trigger created.

SQL>
SQL> spool off;
SQL>


SQL> select status from dba_triggers where trigger_name like'%TRACE_TRIGGER%';

STATUS
--------
ENABLED

To disable the trigger.

SQL> alter trigger trace_trigger disable;

Trigger altered.

SQL> select status from dba_triggers where trigger_name like'%TRACE_TRIGGER%';

STATUS
--------
DISABLED

To enable the trigger.

SQL> alter trigger trace_trigger enable;

Trigger altered.

SQL> select status from dba_triggers where trigger_name like'%TRACE_TRIGGER%';

STATUS
--------
ENABLED

Read more >>

Rman Disaster Recovery Walkthrough.

On Source


Make a backup location.

mkdir -p /u01/backup

Maker sure database is in archive log mode.

Configure control file backup parameters in Rman.

RMAN> configure controlfile autobackup on;

new RMAN configuration parameters:
CONFIGURE CONTROLFILE AUTOBACKUP ON;
new RMAN configuration parameters are successfully stored

RMAN> configure controlfile autobackup format for device type disk to '/u01/backup/cf%F';

new RMAN configuration parameters:
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/u01/backup/cf%F';
new RMAN configuration parameters are successfully stored


Take backup of database plus archivelog.

[oracle@canada ~]$ rman target /

Recovery Manager: Release 11.2.0.1.0 - Production on Sat Oct 5 19:13:05 2013

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

connected to target database: DELL (DBID=3764293269)

RMAN> run
2> {
3> allocate channel c1 device type disk format '/u01/backup/%U';
4> allocate channel c2 device type disk format '/u01/backup/%U';
5> allocate channel c3 device type disk format '/u01/backup/%U';
6> allocate channel c4 device type disk format '/u01/backup/%U';
7> backup database plus archivelog;
8> }

using target database control file instead of recovery catalog
allocated channel: c1
channel c1: SID=51 device type=DISK

allocated channel: c2
channel c2: SID=28 device type=DISK

allocated channel: c3
channel c3: SID=49 device type=DISK

allocated channel: c4
channel c4: SID=34 device type=DISK


Starting backup at 05-OCT-13
current log archived
channel c1: starting archived log backup set
channel c1: specifying archived log(s) in backup set
input archived log thread=1 sequence=3 RECID=1 STAMP=828040174
channel c1: starting piece 1 at 05-OCT-13
channel c2: starting archived log backup set
channel c2: specifying archived log(s) in backup set
input archived log thread=1 sequence=4 RECID=2 STAMP=828040176
input archived log thread=1 sequence=5 RECID=3 STAMP=828040184
channel c2: starting piece 1 at 05-OCT-13
channel c3: starting archived log backup set
channel c3: specifying archived log(s) in backup set
input archived log thread=1 sequence=6 RECID=4 STAMP=828040185
input archived log thread=1 sequence=7 RECID=5 STAMP=828040187
channel c3: starting piece 1 at 05-OCT-13
channel c4: starting archived log backup set
channel c4: specifying archived log(s) in backup set
input archived log thread=1 sequence=8 RECID=6 STAMP=828040188
input archived log thread=1 sequence=9 RECID=7 STAMP=828040446
channel c4: starting piece 1 at 05-OCT-13
channel c1: finished piece 1 at 05-OCT-13
piece handle=/u01/backup/01ollp7v_1_1 tag=TAG20131005T191406 comment=NONE
channel c1: backup set complete, elapsed time: 00:00:00
channel c2: finished piece 1 at 05-OCT-13
piece handle=/u01/backup/02ollp7v_1_1 tag=TAG20131005T191406 comment=NONE
channel c2: backup set complete, elapsed time: 00:00:00
channel c3: finished piece 1 at 05-OCT-13
piece handle=/u01/backup/03ollp7v_1_1 tag=TAG20131005T191406 comment=NONE
channel c3: backup set complete, elapsed time: 00:00:00
channel c4: finished piece 1 at 05-OCT-13
piece handle=/u01/backup/04ollp7v_1_1 tag=TAG20131005T191406 comment=NONE
channel c4: backup set complete, elapsed time: 00:00:01
Finished backup at 05-OCT-13

Starting backup at 05-OCT-13
channel c1: starting full datafile backup set
channel c1: specifying datafile(s) in backup set
input datafile file number=00001 name=/u01/app/oracle/oradata/dell/system01.dbf
channel c1: starting piece 1 at 05-OCT-13
channel c2: starting full datafile backup set
channel c2: specifying datafile(s) in backup set
input datafile file number=00002 name=/u01/app/oracle/oradata/dell/sysaux01.dbf
input datafile file number=00004 name=/u01/app/oracle/oradata/dell/users01.dbf
channel c2: starting piece 1 at 05-OCT-13
channel c3: starting full datafile backup set
channel c3: specifying datafile(s) in backup set
input datafile file number=00005 name=/u01/app/oracle/oradata/dell/example01.dbf
input datafile file number=00003 name=/u01/app/oracle/oradata/dell/undotbs01.dbf
channel c3: starting piece 1 at 05-OCT-13
channel c3: finished piece 1 at 05-OCT-13
piece handle=/u01/backup/07ollp81_1_1 tag=TAG20131005T191408 comment=NONE
channel c3: backup set complete, elapsed time: 00:00:37
channel c2: finished piece 1 at 05-OCT-13
piece handle=/u01/backup/06ollp81_1_1 tag=TAG20131005T191408 comment=NONE
channel c2: backup set complete, elapsed time: 00:01:18
channel c1: finished piece 1 at 05-OCT-13
piece handle=/u01/backup/05ollp81_1_1 tag=TAG20131005T191408 comment=NONE
channel c1: backup set complete, elapsed time: 00:01:50
Finished backup at 05-OCT-13

Starting backup at 05-OCT-13
current log archived
channel c1: starting archived log backup set
channel c1: specifying archived log(s) in backup set
input archived log thread=1 sequence=10 RECID=8 STAMP=828040560
channel c1: starting piece 1 at 05-OCT-13
channel c1: finished piece 1 at 05-OCT-13
piece handle=/u01/backup/08ollpbg_1_1 tag=TAG20131005T191600 comment=NONE
channel c1: backup set complete, elapsed time: 00:00:01
Finished backup at 05-OCT-13

Starting Control File and SPFILE Autobackup at 05-OCT-13
piece handle=/u01/backup/cfc-3764293269-20131005-00 comment=NONE
Finished Control File and SPFILE Autobackup at 05-OCT-13
released channel: c1
released channel: c2
released channel: c3
released channel: c4

Take backup of spfile.


RMAN> backup spfile to destination '/u01/backup/';

Starting backup at 05-OCT-13
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=49 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 05-OCT-13
channel ORA_DISK_1: finished piece 1 at 05-OCT-13
piece handle=/u01/backup/DELL/backupset/2013_10_05/o1_mf_nnsnf_TAG20131005T192028_950694xh_.bkp tag=TAG20131005T192028 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 05-OCT-13

Starting Control File and SPFILE Autobackup at 05-OCT-13
piece handle=/u01/backup/cfc-3764293269-20131005-01 comment=NONE
Finished Control File and SPFILE Autobackup at 05-OCT-13

DBID of database to be restored DBID=3764293269


On new host where database is to be restored
make required directories

[oracle@newyork ~]$ mkdir -p /u01/app/oracle/admin/dell/adump
[oracle@newyork ~]$ mkdir -p /u01/app/oracle/oradata/dell/
[oracle@newyork ~]$ mkdir -p /u01/app/oracle/flash_recovery_area/dell/


Copy backup files to the destination server.

On Destination Server

1) Restore the spfile



[oracle@newyork ~]$ export ORACLE_SID=dell
[oracle@newyork ~]$ rman target /

Recovery Manager: Release 11.2.0.1.0 - Production on Sat Oct 5 19:34:27 2013

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

connected to target database (not started)

RMAN> set dbid=3764293269

executing command: SET DBID

RMAN> startup force nomount;

startup failed: ORA-01078: failure in processing system parameters
LRM-00109: could not open parameter file '/u01/app/oracle/product/11.2.0/db_1/dbs/initdell.ora'

starting Oracle instance without parameter file for retrieval of spfile
Oracle instance started

Total System Global Area     159019008 bytes

Fixed Size                     1335192 bytes
Variable Size                 75497576 bytes
Database Buffers              79691776 bytes
Redo Buffers                   2494464 bytes


RMAN> restore spfile from '/u01/backup/cfc-3764293269-20131005-00';

Starting restore at 05-OCT-13
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=19 device type=DISK

channel ORA_DISK_1: restoring spfile from AUTOBACKUP /u01/backup/cfc-3764293269-20131005-00
channel ORA_DISK_1: SPFILE restore from AUTOBACKUP complete
Finished restore at 05-OCT-13




RMAN> shutdown immediate

Oracle instance shut down



2) Restore controlfile

RMAN> startup nomount

connected to target database (not started)
Oracle instance started

Total System Global Area     272011264 bytes

Fixed Size                     1335952 bytes
Variable Size                201330032 bytes
Database Buffers              67108864 bytes
Redo Buffers                   2236416 bytes





RMAN> run
2> {
3> set controlfile autobackup format for device type disk to '/u01/backup/cf%F';
4> restore controlfile from autobackup;
5> }

executing command: SET CONTROLFILE AUTOBACKUP FORMAT

Starting restore at 05-OCT-13
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=19 device type=DISK

recovery area destination: /u01/app/oracle/flash_recovery_area
database name (or database unique name) used for search: DELL
channel ORA_DISK_1: no AUTOBACKUPS found in the recovery area
channel ORA_DISK_1: looking for AUTOBACKUP on day: 20131005
channel ORA_DISK_1: AUTOBACKUP found: /u01/backup/cfc-3764293269-20131005-01
channel ORA_DISK_1: restoring control file from AUTOBACKUP /u01/backup/cfc-3764293269-20131005-01
channel ORA_DISK_1: control file restore from AUTOBACKUP complete
output file name=/u01/app/oracle/oradata/dell/control01.ctl
output file name=/u01/app/oracle/flash_recovery_area/dell/control02.ctl
Finished restore at 05-OCT-13



3) Restore the database.

RMAN> alter database mount;

database mounted
released channel: ORA_DISK_1


RMAN> catalog start with '   ';  (if backup destination is different from source)



RMAN> restore database;

Starting restore at 05-OCT-13
Starting implicit crosscheck backup at 05-OCT-13
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=19 device type=DISK
Crosschecked 10 objects
Finished implicit crosscheck backup at 05-OCT-13

Starting implicit crosscheck copy at 05-OCT-13
using channel ORA_DISK_1
Finished implicit crosscheck copy at 05-OCT-13

searching for all files in the recovery area
cataloging files...
no files cataloged

using channel ORA_DISK_1

channel ORA_DISK_1: starting datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
channel ORA_DISK_1: restoring datafile 00003 to /u01/app/oracle/oradata/dell/undotbs01.dbf
channel ORA_DISK_1: restoring datafile 00005 to /u01/app/oracle/oradata/dell/example01.dbf
channel ORA_DISK_1: reading from backup piece /u01/backup/07ollp81_1_1
channel ORA_DISK_1: piece handle=/u01/backup/07ollp81_1_1 tag=TAG20131005T191408
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:23
channel ORA_DISK_1: starting datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
channel ORA_DISK_1: restoring datafile 00002 to /u01/app/oracle/oradata/dell/sysaux01.dbf
channel ORA_DISK_1: restoring datafile 00004 to /u01/app/oracle/oradata/dell/users01.dbf
channel ORA_DISK_1: reading from backup piece /u01/backup/06ollp81_1_1
channel ORA_DISK_1: piece handle=/u01/backup/06ollp81_1_1 tag=TAG20131005T191408
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:37
channel ORA_DISK_1: starting datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
channel ORA_DISK_1: restoring datafile 00001 to /u01/app/oracle/oradata/dell/system01.dbf
channel ORA_DISK_1: reading from backup piece /u01/backup/05ollp81_1_1
channel ORA_DISK_1: piece handle=/u01/backup/05ollp81_1_1 tag=TAG20131005T191408
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:58
Finished restore at 05-OCT-13



4) Recover the database

RMAN> recover database;

Starting recover at 05-OCT-13
using channel ORA_DISK_1

starting media recovery

channel ORA_DISK_1: starting archived log restore to default destination
channel ORA_DISK_1: restoring archived log
archived log thread=1 sequence=10
channel ORA_DISK_1: reading from backup piece /u01/backup/08ollpbg_1_1
channel ORA_DISK_1: piece handle=/u01/backup/08ollpbg_1_1 tag=TAG20131005T191600
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:01
archived log file 

name=/u01/app/oracle/flash_recovery_area/DELL/archivelog/2013_10_05/o1_mf_1_10_9507y3bg_.arc thread=1 

sequence=10
channel default: deleting archived log(s)
archived log file 

name=/u01/app/oracle/flash_recovery_area/DELL/archivelog/2013_10_05/o1_mf_1_10_9507y3bg_.arc RECID=9 

STAMP=828042523
unable to find archived log
archived log thread=1 sequence=11
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of recover command at 10/05/2013 19:48:45
RMAN-06054: media recovery requesting unknown archived log for thread 1 with sequence 11 and starting SCN 
of 797450


Note: Ignore the error and relogin to thr rman prompt.





5) open with resetlogs

[oracle@newyork ~]$ rman target /

Recovery Manager: Release 11.2.0.1.0 - Production on Sat Oct 5 19:52:07 2013

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

connected to target database: DELL (DBID=3764293269, not open)

RMAN> sql 'alter database open resetlogs';

using target database control file instead of recovery catalog
sql statement: alter database open resetlogs

RMAN> exit


Recovery Manager complete.


6) verify



[oracle@newyork ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Sat Oct 5 19:54:11 2013

Copyright (c) 1982, 2009, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> archive log list;
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     1
Next log sequence to archive   1
Current log sequence           1


SQL> select name, dbid from v$database;

NAME            DBID
--------- ----------
DELL      3764293269

Read more >>

General Performance Tuning Guidelines for Oracle RAC.

1) Rule of thumb - It is safe to assume that an application which
scales well in a single instance environment would scale well in
a RAC environment. Opposite of that is also true, If an application
has problems with scalability in a single instance environment,
Then it may not scale well in a RAC environment.

2) Speed up instance recovery. 

i) To speed up the instance recovery time use FAST_START_MTTR_TARGET.

 In a single instance environment instance start-up + crash recovery time
 is controlled by this parameter.

Read more >>

Different ways to get the DBID of Database.

Method 1:Through SQL command prompt.

SQL> select dbid from v$database;

      DBID
----------
3764293269

Read more >>

Simulating Oracle Tape Backups.

As per Oracle Note:312737.1

The Oracle DiskSbt API is designed for TESTING purposes ONLY
and can NOT be used for any database backup.

The Oracle.Disksbt can be used to simulate tape backups on disk using sbt_tape
channel.

Read more >>

Oracle Database links.

Primary database name = dell
Secondary Database Name = dup

On Secondary

Create TNS Entry for primary database.

[oracle@newyork admin]$ cat tnsnames.ora 

# tnsnames.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.

Read more >>

RAC common wait events.

1) Global cache blocks lost- This statistic shows block losses during network
transfers. High values of this statistic indicate network problems.
The use of an unreliable IPC protocol, such as UDP, may result in the value
for lost global cache blocks being non-zero. 

High values for this statistics indicates that there is some problem with the IPC,
network or hardware.

2) Global cache blocks corrupt - This statistic shows if there is any block corruption
during interconnect transfers. High value for this statistic indicates
that there is a IPC,network or hardware problem.

Read more >>

How to Tune Shared Pool Cache ?

The one basic rule for tuning the shared pool is to
avoid or minimize parses of any kind, whether they be
soft parses or hard parses.


Parses can only be avoided by your developers by efficiently coding
the application.

As a DBA you can only minimize parses.

Read more >>

How To Read An AWR Report ?

Prerequisites for awrreport.

Statistics level should be set to typical.
Timed statistics should also be enabled.


SQL> show parameter statistics_level 
 
NAME                                 TYPE     VALUE 
------------------------------------ -------- ------------------------------ 
statistics_level                     string   TYPICAL

Read more >>

Convert Oracle Database From Non-ASM to ASM.

Modify parameters

SQL> alter database disable block change tracking;

SQL> alter system set db_create_file_dest='+DATA' scope=spfile;

System altered.

SQL> alter system set db_recovery_file_dest='+FLASH' scope=spfile;

System altered.

Read more >>

Single Instance To RAC Conversion Using RCONFIG.

Nodes Available.

vmlinux1,vmlinux2

Single instance running at vmlinux1

ORACLE_HOME=/u05/app/oracle/product/10.2.0/db_1
SID=racorcl

Read more >>

How to Delete ASM ?

Log in to the asm instance as Oracle User

$ export ORACLE_SID=+ASM

$ sqlplus / as sysdba

Enter the following command to determine whether any Oracle database instance is using the ASM instance: 

Read more >>

How To Clear Oracle Clusterware Installation ?

There are two methods to do it.

Automatic

Run the following scripts as root user.

cd $ORA_CRS_HOME/install/

Read more >>

Single Instance Conversion To RAC Using DBCA.

This tutorial shows how to convert a single instance database to a RAC one by using DBCA.
Below is the configuration of my single instance Database and RAC Nodes.

Single Instance Database.

OS: RHEL4
Oracle Software Version: 10.2.0.4
SID: orascott

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Drop or Delete a RAC Database Using DBCA 10g.

This example shows how to drop a RAC database using DBCA.

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Create Database Template Using DBCA.

In this example i am creating a template of an existing database named "ORASCOTT" by using DBCA.

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Gathering Oracle Database Statistics Using DBMS_STATS.

Gathering Table Statistics.
Check the table for when it was last analyzed.

SQL> select last_analyzed, sample_size from dba_tables where owner='SCOTT' and
     table_name='EMP';

LAST_ANAL SAMPLE_SIZE
--------- -----------
19-MAR-12          14

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Oracle RAC Instance Recovery.

1. All nodes available.

2. One or more RAC instances fail.

3. Node failure is detected by any one of the remaining instances.

4. Global Resource Directory(GRD) is reconfigured and distributed among 
   surviving nodes.

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