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Oracle, Incomplete Recovery & Redo log...

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Regular Advisor

Oracle, Incomplete Recovery & Redo log...

Hi Friends,
When I want to do incomplete recovery (rolling back entire database to previous state/time).

- Do I need to restore redo logs along with datafiles?

- When using "until time", do I need to set nls_date nls_language at the session level?

Regarding the Online-Redo log files.

Theoritically I know that online redo logs can be applied, in the same way as archived logs,
but how ?
do we need to copy the online redo log to the location of "archivelog log" or give full path at the time of applying?

Please help me to understand it.

Thanks in Adv

Let's share the great thing "THE KNOWLEDGE"
Tom Geudens
Honored Contributor

Re: Oracle, Incomplete Recovery & Redo log...

Yes, those online logs can be applied. If oracle cannot find them, it will ask for the exact location. And you can then enter the full path.

Hope this answers one of your questions,
A life ? Cool ! Where can I download one of those from ?
T G Manikandan
Honored Contributor

Re: Oracle, Incomplete Recovery & Redo log...

For your questions

1.For example assume that you need to revert the database to July 8th 10pm

1.restore the backup of the datafile and the control file before this time and you can do a recovery using three options
until cancel
until change
until time

you can use the recover database until time First thing is that the recovery process will automatically look for the archived redo logfiles and update the database upto that point of time.

2.When you are using until time the following format of time is always used

'YYYY-MM-DD:HH24:MI:SS' are speaking about recovery.
When you have reverted your database to old time what is the need for the present redo information on the on-line redolog files.
If you have done a incomplete recovery or done a recovery using a backup controlfile then the database can be opened only be using a
resetlogs option
that is a new incarnation of the database is started from that point.

check for the documentation here.This will give you a clear path.

Bill Thorsteinson
Honored Contributor

Re: Oracle, Incomplete Recovery & Redo log...

Restore the redo logs from the backup from which you are doing
the recovery. This will provide a relatively consistent view of the
database for the recovery process. If you did a cold backup from
a shutdown abort, Oracle may expect to apply data from the redo logs.

As noted the until time is fixed format, and not dependent on NLS parameters.

If you have an online location for archived redo logs Oracle, will try
to find the log files there. If you have all the required log files
uncompressed in the online directory, Oracle will find them on its own.
If they are anywhere else or the names have changed, or the files are
compressed, Oracle will prompt you for the files. You will have to
uncompress the files before Oracle can use them.