Re: standby config --> FAL_SERVER / FAL_CLIENT
- From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 10 Feb 2004 20:15:06 -0000
Just clearing up a point on Maximum Protection
and the meaning of "(does not wait till its applied)".
Isn't this the option where lgwr has to wait for
confirmation that the redo has been written
into the standby log on the standby database
before writing to the online log on the primary
and acknowledging the commit.
One thing to watch out for with standby and
this option is the effect on commits within
pl/sql calls. Oracle does not wait for sync
if you issue a commit inside a pl/sql call,
issuing only one log sync write at the end
of the call - but if you switch to maximum protection,
then every commit inside the call becomes a
log sync call, and performance get much
worse. (I've had one report of a factor of
three for a piece of code doing lots of commits
inside a pl/sql loop).
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
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----- Original Message -----
From: <k.sriramkumar@xxxxxxxxxxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Tuesday, February 10, 2004 12:15 PM
Subject: RE: standby config --> FAL_SERVER / FAL_CLIENT
Hi Prem,
Yes there is a performance overhead with maximize protection. As I said =
earlier, the LGWR process is going to ship the log changes to the =
standby database (does not wait till its applied) and hence It boils =
down to the network connectivity that exists between the primary and the =
standby database. Your overhead is proportional to the network =
bandwidth. Pls test it with a real load before you put in production.
Best Regards
Sriram Kumar
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