Re: supplemental logging questions and golden gate

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@xxxxxxxxx> 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
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