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Recover standby database until cancel using backup controlfile


This question may not be related to standby database per se, but
recover database until cancel .... Command.

Oracle suggests a log sequence #. To apply. I am curious which v$
view(s) oracle looks at to come up with suggested no.


When I look at v$log_history, max(sequence#) is higher than what is
Suggested by oracle at least initially when I create standby database
from
Standby control files and database backup of primary database. After
initial
application of archived logs, max(sequence#() in v$log_history is
same as what is suggested by Oracle.

I am pretty sure Oracle uses some mechanism other than v$log_history.
Appreciate if you can provide any pointers on Oracle's inner workings.

<dbaplusplus@hotmail.com> a écrit dans le message de news: 1177027406.816801.84830@y5g2000hsa.googlegroups.co m...
| Recover standby database until cancel using backup controlfile
|
|
| This question may not be related to standby database per se, but
| recover database until cancel .... Command.
|
| Oracle suggests a log sequence #. To apply. I am curious which v$
| view(s) oracle looks at to come up with suggested no.
|
|
| When I look at v$log_history, max(sequence#) is higher than what is
| Suggested by oracle at least initially when I create standby database
| from
| Standby control files and database backup of primary database. After
| initial
| application of archived logs, max(sequence#() in v$log_history is
| same as what is suggested by Oracle.
|
| I am pretty sure Oracle uses some mechanism other than v$log_history.
| Appreciate if you can provide any pointers on Oracle's inner workings.
|

It starts with the archive containing the lowest scn found in the file headers.

Regards
Michel Cadot

Hi,


> I am pretty sure Oracle uses some mechanism other than v$log_history.
> Appreciate if you can provide any pointers on Oracle's inner workings.

It is little more than V$log_history or low scn from the archive logs.
I will attempt as I am sitting idle in the airport to catch my
(delayed) flight!!

During normal operation, the datafile headers will have the stop scn
set to 0xFFFFFFF.FFFF (or infinity) and the behaviour is almost same
when you say recover database until cancel.If you say until time or
until change, it gets the highscn from the log_history and sets the
stop scn to that number and stops the recovery when it reaches that
stop scn.

Now, we will make a quick visit to the block recovery. When the
trasnaction updates a block, it keeps the XID in the ITL (which is in
the the block header) for the following transaction to help to
construct the read-consistent image of the block.
Any other process trying to get the consistent image will get the UBA
and
Check the following URL for some discussion of relationship between
transactions/rollback segments/ITL.(http://www.quest-pipelines.com/
newsletter/Transaction%20Management.htm) Also while doing the recovery
we reconstruct the block and when the block has open ITLs, we scan the
XID and look for the RBA. RBA has the following format LSN.BLKN.BYTN
where LSN is the Log Sequence Number and BLKN is Block Number and
BYTN is Byte Number within the block. So to recover the block we know
exactly where the redo is stored and we can specifically ask that
particular redo log.


Best Regards,
K Gopalakrishnan
Co-Author: Oracle Wait Interface, Oracle Press 2004
http://www.amazon.com/exec/obidos/tg.../-/007222729X/

Author: Oracle Database 10g RAC Handbook, Oracle Press 2006
http://www.amazon.com/gp/product/007146509X/