> > What version exactly was this? There was some changes in > 8.0.2 in this > > area on win32. The default sync method was also changed at > this point. > > "PostgreSQL 8.0.2 on i686-pc-mingw32, compiled by GCC gcc.exe > (GCC) 3.4.2 (mingw-special)" There we go. That explains it - you have the new code. > > What's the output of "show wal_sync_method"? > > "open_datasync" This setting is only safe if you disable write cache. > > Finally, go into device manager, find your disk, get > properties, look > > under Policies, is the box for "Enable write caching on the disk" > > checked? > > It is checked. > > Does Postgres require this to be unchecked ? It is difficult > to force customers to change it. No, doesn't erquire it. There are a couple of different scenarios: 1) Box is checked. wal_sync_method=open_datasync. This may cause data loss! 2) Box is checked. wal_sync_method=fsync_writethrough. This is safe. 3) Box is unchecked. wal_sync_method=open_datasync. This is safe. 4) Box is unchecked. wal_sync_method=fsync_writethrough. This is safe. In general I would say that 1 is of course the fastest, but it's not safe. 3 should normally be the fastest if the data is on a disk that's only used by postgresql. 2 is probably faster if you have other applications that also write data to the same disk. 4 is probably *never* fastest :-) This all assumes you don't have a battery backed cache. If you have a controller with battery backed cache, 1 should still be the fastest, but now it's suddenly safe. (The basics of these changes are documented in the release notes at http://www.postgresql.org/docs/8.0/static/release-8-0-2.html) //Magnus ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
