Re: A special way of migration

  • From: "Michael McMullen" <ganstadba@xxxxxxxxxxx>
  • To: <MGogala@xxxxxxxxxxxxxxxxxxxx>
  • Date: Wed, 28 Sep 2005 12:46:53 -0400

RE: A special way of migration
I read the concepts before I replied.
I just don't understand how consistent=y will "The whole export will be read
into undo segments,"

The user doing the dml will "build" rollback segments. The user doing the
export will require a read consistent image by using the rollback segments.
If the user doing the dml commits, the user doing the export is subject to
"ORA-01555" (at least I think that is the number for snapshot to old).

I'm doing a full export of a database right now with consistent=y that I
only update at night. I don't see any undo being assigned to my export user.

----- Original Message ----- 
From: Gogala, Mladen
To: 'makbo@xxxxxxxxxxx'
Cc: ORACLE-L@xxxxxxxxxxxxx
Sent: Wednesday, September 28, 2005 12:26 PM
Subject: RE: A special way of migration

Unfortunately, it's not a misinformation. With "consistent=y", you will have
SET TRANSACTION READ ONLY as the first statement in the export. What does
this statement do you can read for yourself in the manual. It wasn't an
overuse of sarcasm.
As far as logical backup goes, I would tend not to disagree, but it has
nothing to do with CONSISTENT=YES. This "read consistent export" can only
ensure consistency with respect to certain point in time if it builds a
read-consistent image of the database with respect to that point in time.
You have three guesses to guess which structures are used for building
such a consistent image.
So Mark, please read the fine manual before you accuse me of being overly
Mladen Gogala

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