Recovering using backup controlfile

Question

Hello,
When we do database recovery (not until some time in the past, but until "now") using binary backup of controlfile why do we need to open it with resetlogs?
The scenario is: we have all the datafiles, archived redo and online redo logs, but all of the controlfile are lost. We have backup of controfile and we need to restore and recover it. I've read we need to open the db with resetlogs then. Why?
I heard we don't need to do this if there was backup of the controlfile to text trace. I also don't understand why.
Thanks in advance for help
Aliq

Answer 1

Navneet wrote:
Hi,
In case when controlfile i lost and restored from the bcakup, Datafiles are uptodate with the redo log files but controlfiles are behind,
WHen we say "Recover databse using backup controlfile" this means we are applying the archives to the datafiles as well as controlfiles. But datafiles are uptodate aor they will remain untopuched and controlfile wil be updated to the recnt redo.
Now the quetion is why we need reetlogs even when we are doing complete recovery?
So the reasin for this is controlfile needs to be updated with some datastructure updatations and those updations are performed during resetlog option. These data structure updatation may contain some changes in the properties of datafiles,blocks, or somethng internal processes of ORacle.
So we need to use resetlogs.
Regards,
NavneetNavneet,
Control flies are going to get updated from the datafile info which are going to get update from the archived logs.We never apply archive logs to the control file , they are meant for datafiles only.
Now the quetion is why we need reetlogs even when we are doing complete recovery?
So the reasin for this is controlfile needs to be updated with some datastructure updatations and those updations are performed during resetlog option. These data structure updatation may contain some changes in the properties of datafiles,blocks, or somethng internal processes of ORacle.
So we need to use resetlogs.
Hmm well I am afraid that its plainly wrong. Resetlog is required because we are stopping the recovery in between. This means whatever we have done and is stored in the archived logs , we can't apply it all. Now we have thrown datafiles and control file back in the time but redo logs never come back. So we are starting from fresh with resetlogs which will make the seuence numbers 0,1 and lets open the db. After the db is open, the sequence numbers are matched with the stored ones in the controlfile and datafile.
Aman....