Thread: 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.


See: http://www.freebsd.org/releases/4.4R/relnotes-i386.html

> 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)
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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