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

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Tue, Jan 8, 2013 at 7:17 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> ... 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.

> For the record, I don't believe those problems would be particularly
> hard to solve.

Well, the problem of "find out the box's physical RAM" is doubtless
solvable if we're willing to put enough sweat and tears into it, but
I'm dubious that it's worth the trouble. The harder part is how to know
if the box is supposed to be dedicated to the database. Bear in mind
that the starting point of this debate was the idea that we're talking
about an inexperienced DBA who doesn't know about any configuration knob
we might provide for the purpose.

I'd prefer to go with a default that's predictable and not totally
foolish --- and some multiple of shared_buffers seems like it'd fit the
bill.

regards, tom lane