Re: [SPAM] Re: [SPAM] Re: WAL directory size calculation

Hi Moreno:

On Wed, Aug 3, 2016 at 1:07 PM, Moreno Andreo <moreno(dot)andreo(at)evolu-s(dot)it> wrote:

It's already been answered, but as it seems to be answering a chunk of
my mail...

> Should I keep fsync off? I'd think it would be better leaving it on, right?

Yes. If you have to ask wether fsync should be on, it should.

I mean, you only take it off when you are absolutely sure of where you
are doing, fsync off goes against the D in acid.

You normally only turn it off in counted cases. As an example we have
an special postgresql.conf for full cluster restores, with fsync=off.
Wehen we need it we stop the cluster, boot it with that, restore, stop
it again and reboot with the normal fsync=on config. In this case we
do not mind losing data as we are doing a full restore anyway.

But normally, its a bad idea. As a classic photo caption says,
fsync=off => DBAs running with scissors.

Francisco Olarte.