The infamous event "log file sync"will basically disapear. So you can see what this does to the system, by looking v$system_event to see how much "log file sync" there is.
Anjo. ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Thursday, November 20, 2003 4:10 PM parallel > I think my understanding was wrong. _wait_for_sync actually only changes the > behavior of foreground processes. When set to false, they don't wait for LGWR > to write redo records to disk; instead they continue to do their work as if log > file sync already finished. It *does not* change any behavior of LGWR, > notification or not. Correct me if I'm wrong again. > > I'm still interested in Tanel's benchmark, though. Only that is scientific. > > Yong Huang > > --- Yong Huang <[EMAIL PROTECTED]>, i.e. myself, wrote a few minutes ago: > > Tanel, > > > > Did you observe better performance? By how much? Do please let us know! > > > > From what I read, _wait_for_sync when set to false means LGWR immediately > > notifies user (foreground) processes that redo record writes are done (even > > though they're not). When you say the parameter only affects LGWR, you need > > to > > clarify what you mean by "affect"; it changes the notification (posting) > > behavior of LGWR therefore changes the behavior of waiting processes (*when* > > they stop waiting). Just semantics. > > > > Yong Huang > > > > --- Tanel Poder <[EMAIL PROTECTED]> wrote: > > > Anjo, > > > > > > I also thought it affects only lgwr sync, but Jonathan Lewis once told that > > > it affects any disk writes... > > > > > > If it affects only lgwr, then great, I can make Apps upgrades, which do > > > really lots of DDLs and small transactions, quite much faster that way... > > > > > > Thank you, > > > Tanel. > > > > > > > > > > _wait_for_sync basically meant that a session is waiting for the sync > > > > of the > > > > redo by the lgwr. Normally the redo log writer writes to disk and then > > > > notifies the session that the transaction is completed. By setting > > > > this to > > > > false, you no longer wait for the redo to go to disk. > > > > > > > > That has no impact on your situation. > > > > > > > > Anjo. > > > __________________________________ > Do you Yahoo!? > Free Pop-Up Blocker - Get it now > http://companion.yahoo.com/ > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: Yong Huang > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Anjo Kolk INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
