Re: Database Link to check Standby Database

ITAPORT06 wrote:

> Mark thanks a lot for your response. 
> Sorry for not mentioning:  The release is 8.1.7.4 
> 
> I have two seperate servers PROD and STANDBY so I gues u mean Physical
> standby.
> 
> What I like to achieve is to check the production & Standby server to
> check both squence numbers of the last create and applied redo log
> files. I want to do this " from  "  the production server by comparing
> the sequence numbers of both servers. This has to be done autmatic. 
> 
> What will happen if I create a DB link to a Standby server.  Because
> the redo log with the create DB link command wil also be applied on
> the standby server. 
>  
> Thanks, 
> 
> Ton 
> 

What I replied the first time is still pretty much the case.

If you create the link in the primary, it will be created in the physical standby also, which is irrelevant to your goal. You need to do a test to convince yourself that this won't help. Using a DB link requires the remote database to be open. Your physical standby will not normally be open.

If you are using managed recovery, the documentation tells you how to check the the appropriate V$ table on either the primary or the standby, as I mentioned. If you are doing manual (user-managed) recovery, your own scripts will have to do the checking. For example, you could extract the date and time, or SCN, for the last applied redo log from the recovery session output and compare it to the current time or SCN of the primary.

--Mark Bole

>
[...]
>>
>>In a physical standby, the Dataguard documentation specifically mentions
>>V$ARCHIVE_DEST_STATUS as a way to determine managed recovery progress
>>and gives a sample query. This view is (should be) identical on both the
>>primary and the standby, so you could just check it on the primary and
>>forget the link.
>>
>>The documentation gives several other examples using V$ARCHIVED_LOG and
>>V$LOG_HISTORY as well, in case you are doing manual recovery. You don't
>>need a DB link for this, you could connect directly from SQL*Plus or
>>some other client -- but link or otherwise, only if the standby is
>>opened temporarily in read-only mode (which is the only way to open a
>>physical standby without destroying its standby status).
>>
>>A different view (dba_logstdby_progress) exists for the same purpose in
>>a logical standby. With a logical standby database, the documentation
>>calls for creating various links between the primary and standby in case
>>a table needs to be re-instantiated or in case you are doing a
>>switchover for disaster recovery (the latter is considered to be
>>somewhat buggy and unreliable for version 9iR2).
>>
>>--Mark Bole
Received on Wed Aug 25 2004 - 04:24:48 CDT