Re: Additional redo for supplemental logging at table level

  • From: David Mann <dmann99@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Wed, 28 Dec 2011 09:59:05 -0500

>Hi,
>I would like to know if anyone has done any testing on how much
>additional redo is generated if supplemental log groups are created on
>tables. I know that it will depend on the number of columns in a log
>group, column size, data type, etc., but I just want to get an idea
>about generally how much additional information (in terms of %age) is
>generated for DML statements.

I did do formal testing of this for a previous Golden Gate
implementation. I don't have exact numbers in front of me but our db
was 600gb at the time, we were replicating 400 of 1000 tables (some of
the busiest out of the 1000), and generated about 10gb redo a day.
After going through all of this we saw our numbers go up by a couple
of logs a day but I would definitely say in our case it was max 5%
more if that. Of course your mileage may vary depending on the makeup
of your DB and types of updates you are throwing at it. Basically
everyone was freaking out over nothing :)

-Dave

-- 
Dave Mann
www.brainio.us
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