Progress status of an index rebuild or creation, or other long operations.

When we launch a long operation, such as a RMAN backup or rebuild of a large index, we can come to despair of not having an estimate of the time it may take. We can even come to think that is doing nothing.

For the progress of a long operation we can query the view V$SESSION_LONGOPS, first obtaining the process ID from V$SESSION. In the case of DBA, we know exactly which user is rebuilding the index, so we can simplify it into a single query.

The following example shows the progress of the reconstruction of a partition of an index. It was launched using the PARTITION modifier, so that various processes were created in the instance:

SELECT MESSAGE FROM V$SESSION_LONGOPS WHERE SID IN (SELECT SID FROM V$SESSION WHERE USERNAME='SYS' AND STATUS='ACTIVE') ORDER BY START_TIME;

Rowid Range Scan: APPU.RT_SK: 111958 out of 111958 Blocks done
Rowid Range Scan: APPU.RT_SK: 99670 out of 99670 Blocks done
Rowid Range Scan: APPU.RT_SK: 50518 out of 50518 Blocks done
Rowid Range Scan: APPU.RT_SK: 238934 out of 238934 Blocks done
Rowid Range Scan: APPU.RT_SK: 38230 out of 38230 Blocks done
Rowid Range Scan: APPU.RT_SK: 42273 out of 42273 Blocks done
Rowid Range Scan: APPU.RT_SK: 1160535 out of 1160535 Blocks done

Oracle considers "long operation" any operation longer than 6 seconds

COURTESY:ORACLE FAQ'S.

Oracle Database 11g: The Top Features for DBAs : Backup and Recovery

Backup and Recovery

Advice on data recovery just a one of the new gems available from RMAN in Oracle Database 11g.

Data Recovery Advisor

Consider the error shown below:

SQL> conn scott/tiger

Connected.

SQL> create table t (col1 number);

create table t (col1 number)

*

ERROR at line 1:

ORA-01116: error in opening database file 4

ORA-01110: data file 4: '/home/oracle/oradata/PRODB3/users01.dbf'

ORA-27041: unable to open file

Linux Error: 2: No such file or directory

Additional information: 3

Does it look familiar? Regardless of your experience as a DBA, you probably have seen this message more than once. This error occurs because the datafile in question is not available—it could be corrupt or perhaps someone removed the file while the database was running. In any case, you need to take some proactive action before the problem has a more widespread impact.
In Oracle Database 11g, the new Data Recovery Advisor makes this operation much easier. The advisor comes in two flavors: command line mode and as a screen in Oracle Enterprise Manager Database Control. Each flavor has its advantages for a given specific situation. For instance, the former option comes in handy when you want to automate the identification of such files via shell scripting and schedule recovery through a utility such as cron or at. The latter route is helpful for novice DBAs who might want the assurance of a GUI that guides them through the process. I'll describe both here.

Command Line Option

The command line option is executed through RMAN. First, start the RMAN process and connect to the target.

$ rman target=/

Recovery Manager: Release 11.1.0.5.0 - Beta on Sun Jul 15 19:43:45 2007

Copyright (c) 1982, 2007, Oracle.  All rights reserved.

connected to target database: PRODB3 (DBID=3132722606)

Assuming that some error has occurred, you want to find out what happened. The list failure command tells you that in a jiffy.

RMAN> list failure;

If there is no error, this command will come back with the message:

no failures found that match specification

If there is an error, a more explanatory message will follow:

using target database control file instead of recovery catalog

List of Database Failures

=========================

Failure ID Priority Status    Time Detected Summary

----------      --------     ---------     -------------       -------

142        HIGH     OPEN      15-JUL-07     One or more non-system datafiles are missing

This message shows that some datafiles are missing. As the datafiles belong to a tablespace other than SYSTEM, the database stays up with that tablespace being offline. This error is fairly critical, so the priority is set to HIGH. Each failure gets a Failure ID, which makes it easier to identify and address individual failures. For instance you can issue the following command to get the details of Failure 142.

RMAN> list failure 142 detail;

This command will show you the exact cause of the error.

Now comes the fun part: How do you rectify the error? Seasoned DBAs will probably ace this without further help but novice DBAs (and even experienced but tired ones) will welcome some guidance here. They can turn to Data Recovery Advisor for assistance:

RMAN> advise failure;

It responds with a detailed explanation of the error and how to correct it:

List of Database Failures

=========================

Failure ID Priority Status    Time Detected Summary

----------      --------     ---------     -------------       -------

142        HIGH     OPEN      15-JUL-07     One or more non-system datafiles are missing

analyzing automatic repair options; this may take some time

using channel ORA_DISK_1

analyzing automatic repair options complete

Mandatory Manual Actions

========================

no manual actions available

Optional Manual Actions

=======================

1. If file /home/oracle/oradata/PRODB3/users01.dbf was unintentionally renamed or moved, restore it

Automated Repair Options

========================

Option Repair Description

------ ------------------

1      Restore and recover datafile 4  

  Strategy: The repair includes complete media recovery with no data loss

  Repair script: /home/oracle/app/diag/rdbms/prodb3/PRODB3/hm/reco_3162589478.hm

This output has several important parts. First, the advisor analyzes the error. In this case, it's pretty obvious: the datafile is missing. Next, it suggests a strategy. In this case, this is fairly simple as well: restore and recover the file. (Please note that I have deliberately chosen a simple example to focus the attention on the usage of the tool, not to discuss the many cases where the database could fail and how they can be recovered. The dynamic performance view V$IR_MANUAL_CHECKLIST also shows this information.)

However, the most useful task Data Recovery Advisor does is shown in the very last line: it generates a script that can be used to repair the datafile or resolve the issue. The script does all the work; you don't have to write a single line of code.
Sometimes the advisor doesn't have all the information it needs. For instance, in this case, it does not know if someone moved the file to a different location or renamed it. In that case, it advises to move the file back to the original location and name (under Optional Manual Actions).
OK, so the script is prepared for you. Are you ready to execute it? I don't know about you, but I would verify what the script actually does first. So, I issue the following command to "preview" the actions the repair task will execute:

RMAN> repair failure preview;

Strategy: The repair includes complete media recovery with no data loss

Repair script: /home/oracle/app/diag/rdbms/prodb3/PRODB3/hm/reco_741461097.hm

contents of repair script:

   # restore and recover datafile

   sql 'alter database datafile 4 offline';

   restore datafile 4;

   recover datafile 4;

   sql 'alter database datafile 4 online';

This is good; the repair seems to be doing the same thing I would have done myself using RMAN. Now I can execute the actual repair by issuing:

RMAN> repair failure;

Strategy: The repair includes complete media recovery with no data loss

Repair script: /home/oracle/app/diag/rdbms/prodb3/PRODB3/hm/reco_3162589478.hm

contents of repair script:

   # restore and recover datafile

   sql 'alter database datafile 4 offline';

   restore datafile 4;

   recover datafile 4;

   sql 'alter database datafile 4 online';

Do you really want to execute the above repair (enter YES or NO)?

Assuming I'm OK, I answer YES and the action goes on:

executing repair script

 

sql statement: alter database datafile 4 offline

 

Starting restore at 15-JUL-07

using channel ORA_DISK_1

 

channel ORA_DISK_1: restoring datafile 00004

input datafile copy RECID=5 STAMP=628025835 file name=/home/oracle/flasharea/PRODB3/datafile/o1_mf_users_39ocxbv3_.dbf

destination for restore of datafile 00004: /home/oracle/oradata/PRODB3/users01.dbf

channel ORA_DISK_1: copied datafile copy of datafile 00004

output file name=/home/oracle/oradata/PRODB3/users01.dbf RECID=0 STAMP=0

Finished restore at 15-JUL-07

 

Starting recover at 15-JUL-07

using channel ORA_DISK_1

 

starting media recovery

 

archived log for thread 1 with sequence 51 is already on disk as file /home/oracle/flasharea/PRODB3/archivelog/2007_07_15/o1_mf_1_51_39ocxxdw_.arc

...  

                              

and so on ...

name=/home/oracle/flasharea/PRODB3/archivelog/2007_07_15/o1_mf_1_55_39ocy9ox_.arc thread=1 sequence=55

media recovery complete, elapsed time: 00:00:01

Finished recover at 15-JUL-07

 

sql statement: alter database datafile 4 online

repair failure complete

 

RMAN>

Note how RMAN prompts you before attempting to repair. In a scripting case, you may not want to do that; rather, you would want to just go ahead and repair it without an additional prompt. In such a case, just use repair failure noprompt at the RMAN prompt.

 Courtesy : Oracle.com/11g New Features

 

DUAL table and it’s Specialty

Here I start my first post on my own blog with this basic oracle stuff. When I started my carrier as a DBA many times thought about why it’s so different to that of other tables... finally keeping all of you guys on the loop about it

Friends, many of us know about DUAL and its usage. Let’s learn few things about it…

1) Can we drop a dual table?

Ans: Yes. But it will have serious impact on the database functionality. So you should never do that

2) Can we create DUAL table if dropped?

Ans: Yes. use the following steps for the same…

SQL> DROP TABLE SYS.DUAL ;

Table dropped.

SQL> CREATE TABLE SYS.DUAL
2 (
3 DUMMY VARCHAR2(1 BYTE)
4 )
5 TABLESPACE SYSTEM;

Table created.

SQL> CREATE PUBLIC SYNONYM DUAL FOR SYS.DUAL;

Synonym created.

SQL> GRANT SELECT ON SYS.DUAL TO PUBLIC WITH GRANT OPTION;

Grant succeeded.

SQL> INSERT INTO dual VALUES (‘X’);

1 row created.

SQL> SELECT * FROM dual;

D
-
X

TOM KYTE explained about this in one of his articles and as always its best…

http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1562813956388

All above ask your friend GOOGLE about this, lot of results will hit your door

HAPPY LEARNING…