Re: standby config --> FAL_SERVER / FAL

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Tue, 10 Feb 2004 20:15:06 -0000
Message-ID: <006801c3f012$9a39e970$6702a8c0@Primary>

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
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Original Message ----- From: <k.sriramkumar_at_iflexsolutions.com> To: <oracle-l_at_freelists.org> 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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Received on Tue Feb 10 2004 - 14:15:06 CST

Re: standby config --> FAL_SERVER / FAL_CLIENT