O_DIRECT

The O_DIRECT flag has been added in FreeBSD 4.4 (386 & Alpha) also. From
the release notes:

Kernel Changes

The O_DIRECT flag has been added to open(2) and fcntl(2). Specifying this
flag for open files will attempt to minimize the cache effects of reading
and writing.

I wonder if using this for WAL would be good.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
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The O_DIRECT flag has been added to open(2) and fcntl(2). Specifying

this

flag for open files will attempt to minimize the cache effects of

reading

and writing.

I wonder if using this for WAL would be good.

Not before the code is not optimized to write more than the current 8k
to
the WAL at a time.
(The killer currently are larger transactions that produce approx more
than 64k WAL, (try the open_datasync setting with "copy from"))

Andreas