I looked this over and I am unsure what this does for us that isn't already accomplished using the wal_sync_method settings. See xlog.c for a description of O_DIRECT and when it is used.
--------------------------------------------------------------------------- ITAGAKI Takahiro wrote: > Bruce Momjian <pgman@candle.pha.pa.us> wrote: > > > > > > Here is a small patch to prevent undesired WAL file caching by kernel. > > > > > posix_fadvise(POSIX_FADV_DONTNEED) attempts to free cached pages and > > > > > the kernel will discard them in preference to other data caches. > > > > > > > > On plenty of platforms, this won't even compile ... > > > > Yes, but we probably have to have a configure test to see if > > posix_fadvise exists too. I will keep this for 8.2. > > I think we can use _POSIX_ADVISORY_INFO to test if posix_fadvise exists. > Also, I added the check on whether WAL archiving is enabled, because > archivers might use the caches to read the WAL segment. > > > By the way, should we put posix_fadvise on the separated place with renaming > pg_fadvise? If we use posix_fadvise in other purposes, for example, > read-ahead control, the separation would be good to keep codes clean. > > --- > ITAGAKI Takahiro > NTT Cyber Space Laboratories > [ Attachment, skipping... ] > > ---------------------------(end of broadcast)--------------------------- > TIP 9: In versions below 8.0, the planner will ignore your desire to > choose an index scan if your joining column's datatypes do not > match -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (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 1: 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
