Re: system change number on a physical standby database

From: Simone Fumasoli <>
Date: Wed, 18 Apr 2018 11:05:10 +0200
Message-ID: <>

If you are speaking about the conversion between physical and snapshot standby: when the database is switched, a guaranteed flashback point is created before being opened in read/write mode. The archive logs from the primary database are still retrieved but not applied, so they are effectively different databases each one doing different work. Since the SCN changes for every commit, and sice the now diverging databases will undergo commits in different number and time, they will have different SCNs.

Once you revert the snapshot DB back to physical standby, it will be flashed back to the flashback point created at first and the two databases will be back being virtually aligned. I say virtually because there will tipically be, even with no lag whatsoever, a couple number difference, so they will realistically not be exactly the same in any case.


2018-04-18 5:50 GMT+02:00 james Jose <>:

> system change number on physical standby database and primary database are
> same,correct?
> The moment the physical standby is converted to an active test
> database(read/write mode),The system change number we capture on the
> standby database will still match with primary or will it be different?
> Thanks

Received on Wed Apr 18 2018 - 11:05:10 CEST

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