> Well, O_DIRECT has finally made it into the Linux kernel. It lets you > open a file in such a way that reads and writes don't go to the buffer > cache but straight to the disk. Accesses must be aligned on > filesystem block boundaries. > > Is there any case where PG would benefit from this? I can see it > reducing memory pressure and duplication of data between PG shared > buffers and the block buffer cache. OTOH, it does require that writes > be batched up for decent performance, since each write has an implicit > fsync() involved (just as with O_SYNC). > > Anyone played with this on systems that already support it (Solaris?)
I have heard there are many cases there O_DIRECT on Solaris is slower for databases than normal I/O. I think bulk copy was faster but not normal operation. Probably not something we are going to get into soon. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
