Christopher Kings-Lynne wrote: > > I'm likely going to make this the default for PostgreSQL on FreeBSD > > starting with 7.4 (just posted something to -hackers about this)f. If > > you'd like to do this in your testing, just apply the following patch. > > > > Right now PostgreSQL defaults to 8K blocks, but FreeBSD uses 16K > > blocks which means that currently, reading two blocks of data in PG is > > two read calls to the OS, one reads 16K of data off disk and returns > > the 1st page, the 2nd call pulls the 2nd block from the FS cache. In > > making things 16K, it avoids the need for the 2nd system call which is > > where the performance difference is coming from, afaikt. -sc > > Are you _sure_ this won't cause any atomicity problems? Can FreeBSD write > 16k as an atomic unit?
We pre-modified page images to WAL before modifying the page. The disks are only 512-byte blocks, so we don't rely on file system atomicity anymore anyway. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
