This factor of 3 was a single example, not a general conclusion. The first important point that made this visible was that the sample code was committing inside a fast pl/sql loop, and contrary to the statement in the manuals about sessions waiting for lgwr, a session does not generally wait for a commit (log file sync) inside a pl/sql construct. However, if the pl/sql loop includes a distributed transaction or (it seems) has a standby database in maximum protection mode, the session suddenly DOES wait for a log file sync - and this has a big impact on performance. Once this factor has appeared, any extra time for the commit is simply down to network latency and time to write at the far end (for as many far ends as there may be) - the big issue is that you moved from not waiting for commit to waiting for commit. Regards Jonathan Lewis http://www.jlcomp.demon.co.uk The educated person is not the person who can answer the questions, but the person who can question the answers -- T. Schick Jr Next public appearances: March 2004 Hotsos Symposium - The Burden of Proof March 2004 Charlotte NC OUG - CBO Tutorial April 2004 Iceland One-day tutorials: http://www.jlcomp.demon.co.uk/tutorial.html Three-day seminar: see http://www.jlcomp.demon.co.uk/seminar.html ____UK___February ____UK___June The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.html ----- Original Message ----- From: <k.sriramkumar@xxxxxxxxxxxxxxxxxx> To: <oracle-l@xxxxxxxxxxxxx> Sent: Wednesday, February 11, 2004 4:37 AM Subject: RE: standby config --> FAL_SERVER / FAL_CLIENT Hi Jonathan, Thanks for highlighting the same. I have one question on this and hope = you would help me out. This factor of three as I understand is that if a = normal commit takes a factor time/wait? Pls explain) of x then maximum = protection mode would be a factor of 3x.=20 Also this 3x factor is for a single standby instance and would increase = 3x times for every additional setup of standby databases. Is my = understanding correct? Best Regards Sriram Kumar -----Original Message----- From: Jonathan Lewis [mailto:jonathan@xxxxxxxxxxxxxxxxxx]=20 Sent: Wednesday, February 11, 2004 1:45 AM To: oracle-l@xxxxxxxxxxxxx Subject: Re: standby config --> FAL_SERVER / FAL_CLIENT 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=20 into the standby log on the standby database=20 before writing to the online log on the primary=20 and acknowledging the commit. One thing to watch out for with standby and this option is the effect on commits within=20 pl/sql calls. Oracle does not wait for sync if you issue a commit inside a pl/sql call,=20 issuing only one log sync write at the end=20 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 The educated person is not the person=20 who can answer the questions, but the=20 person who can question the answers -- T. Schick Jr Next public appearances: March 2004 Hotsos Symposium - The Burden of Proof March 2004 Charlotte NC OUG - CBO Tutorial April 2004 Iceland One-day tutorials: http://www.jlcomp.demon.co.uk/tutorial.html Three-day seminar: see http://www.jlcomp.demon.co.uk/seminar.html ____UK___February ____UK___June The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.html ----- Original Message -----=20 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 = =3D earlier, the LGWR process is going to ship the log changes to the =3D standby database (does not wait till its applied) and hence It boils =3D down to the network connectivity that exists between the primary and the = =3D standby database. Your overhead is proportional to the network =3D bandwidth. Pls test it with a real load before you put in production. Best Regards Sriram Kumar ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html ----------------------------------------------------------------- DISCLAIMER: This message contains privileged and confidential information and is = intended only for the individual named.If you are not the intended = recipient you should not disseminate,distribute,store,print, copy or = deliver this message.Please notify the sender immediately by e-mail if = you have received this e-mail by mistake and delete this e-mail from = your system.E-mail transmission cannot be guaranteed to be secure or = error-free as information could be = intercepted,corrupted,lost,destroyed,arrive late or incomplete or = contain viruses.The sender therefore does not accept liability for any = errors or omissions in the contents of this message which arise as a = result of e-mail transmission. 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