On 07/22/2013 03:30 PM, Миша Тюрин wrote:
>
> i tell about wal_level is higher than MINIMAL
OK, so you want to be able to force O_DIRECT for wal_level = archive ?
I guess that makes sense if you expect the archive_command to read the
file out of the RAID controller's write cache before it gets flushed and
your archive_command can also use direct I/O to avoid pulling it into cache.
You already know where to change to start experimenting with this. What
exactly are you trying to ask? I don't see any risk in forcing O_DIRECT
for higher wal_level, but I'm not an expert in WAL and recovery. I'd
recommend testing on a non-critical PostgreSQL instance.
-- Craig Ringer http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services