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).
