Re: supplemental logging questions and golden gate
Date: Fri, 22 Jul 2011 10:30:35 -0400
Message-ID: <CAMVw97JduLr_apQMTq+xWotXvX2QrhP-4e9JBwMbj0NRjGRsXw_at_mail.gmail.com>
By default Oracle logs only columns that changed. The whole purpose of supplemental logging is to enable logging for something that didn't.
If you execute
update emp set name='Bob' where emp_id=100
you won't get emp_id logged in the redo because it did not change unless you enable supplemental logging for emp_id column (which is required on the receiving end of the replication to resolve the row being updated). The whole before/after image point, when applied to supplemental logged columns, is a bit moot since the column value did not change. The "before image" term in the doc might be a bit confusing until you realize that.
On Fri, Jul 22, 2011 at 10:08 AM, Dba DBA <oracledbaquestions_at_gmail.com> wrote:
> I am confused. I thought supplemental logging only needs to log the before
> image of every column, if you do not log based on a unique or primary key?
> If you do, it only gets the before image of the column that changed.
> However, that before image should already be logged to redo, since that
> image is copied to the undo tablespace and that generates redo.
>
-- Alex Fatkulin, http://afatkulin.blogspot.com http://www.linkedin.com/in/alexfatkulin -- http://www.freelists.org/webpage/oracle-lReceived on Fri Jul 22 2011 - 09:30:35 CDT