Re: proposal: Set effective_cache_size to greater of .conf value, shared_buffers

Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Jan 8, 2013 at 9:53 AM, Claudio Freire <klaussfreire@gmail.com> wrote:
>> Rather, I'd propose the default setting should be "-1" or something
>> "default" and "automagic" that works most of the time (but not all).

> A cruder heuristic that might be useful is 3 * shared_buffers.

Both parts of that work for me.  It's certainly silly that the default
value of effective_cache_size is now equivalent to the default value
of shared_buffers.  And I don't especially like the idea of trying to
make it depend directly on the box's physical RAM, for the same
practical reasons Robert mentioned.

It might be better to use 4 * shared_buffers, as that corresponds to the
multiple that's been the default since 8.2 or so (ie 128MB vs 32MB), and
3x just seems kinda oddball.
        regards, tom lane