On 22/03/15 05:42, David G. Johnston wrote:
On Sat, Mar 21, 2015 at 8:54 AM, Tom Lane <t...@sss.pgh.pa.us
<mailto:t...@sss.pgh.pa.us>>wrote:
Stephen Frost <sfr...@snowman.net <mailto:sfr...@snowman.net>> writes:
> At the moment, one could look at our default postgresql.conf and the
> "turns forced synchronization on or off" and think it's
something akin
> or somehow related to synchronous_commit (which is completely
different,
> but the options are right next to each other..).
> How about a big warning around fsync and make it more indepenent
from
> the options around it?
Yeah, the main SGML docs are reasonably clear about the risks of
fsync,
but postgresql.conf doesn't give you any hint that it's
dangerous. Now
I'm not entirely sure that people who frob postgresql.conf without
having
read the docs can be saved from themselves, but we could do something
like this:
# - Settings -
#wal_level = minimal # minimal, archive,
hot_standby, or logical
# (change requires restart)
#fsync = on # turns forced
synchronization on or off
+ # (fsync=off is dangerous,
read the
+ # (manual before using it)
#synchronous_commit = on # synchronization level;
# off, local,
remote_write, or on
#wal_sync_method = fsync # the default is the first
option
# supported by the
operating system:
Also, I think the short description "turns forced synchronization
on or
off" could stand improvement; it really conveys zero information.
Maybe
something like "force data to disk when committing"?
Also, whatever we do here should be reflected into the description
strings
in guc.c.
" ​enables or disables data durability ​promise of ACID." ?
David J.
What does ACID mean???
I don't want to trip out on acid, and if I do, I don't want it hanging
around. Safer to set this to off!!!
I actual do know what ACID means, but some 'children' have write access
to a the postgresql.conf file without adequate 'adult' supervision!
Cheers,
Gavin
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