Re: Remove fsync ON/OFF as a visible option?

On 22/03/15 05:42, David G. Johnston wrote:
> On Sat, Mar 21, 2015 at 8:54 AM, Tom Lane <tgl@sss.pgh.pa.us 
> <mailto:tgl@sss.pgh.pa.us>>wrote:
>
>     Stephen Frost <sfrost@snowman.net <mailto:sfrost@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