>> This is what we have discovered. AFAIK, all other major databases or >> other similar apps (like exchange or AD) all open files with >> FILE_FLAG_WRITE_THROUGH and do *not* use fsync. It might >give noticably >> better performance with an O_DIRECT style WAL logging at >least. But I'm >> unsure if the current code for O_DIRECT works on win32 - I think it >> needs some fixing for that. Which might be worth looking at for 8.1. > >Doesn't Windows support O_SYNC (or even better O_DSYNC) flag to open()? >That should be the Posixy spelling of FILE_FLAG_WRITE_THROUGH, if the >latter means what I suppose it does.
They should, but someone said it didn't work. I haven't followed up on it, though, so it is quite possible it works. If so, it is definitly worth trying. >> Not much to do about the bgwriter, the way it is designed it *has* to >> fsync during checkpoint. > >Theoretically at least, the fsync during checkpoints should not be a >performance killer. If you run a tight benchmark past a checkpoint, it will make an effect if the fsync takes twice as long as it does on unix. If the checkpoint happens when other I/O is fairly low then it shuold not have an effect. Merlin, was that by any chance you? We've been talking about these things quite a lot :-) >So: try O_SYNC instead of fsync for WAL, ie, wal_sync_method = >open_sync or open_datasync. Definitly worth cehcking out. //Magnus ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly