Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Tue, Apr 26, 2011 at 9:04 PM, Merlin Moncure <mmoncure(at)gmail(dot)com> wrote:
>> The very first thing to check is effective_cache_size and to set it to
>> a reasonable value.
> Actually, effective_cache_size has no impact on costing except when
> planning a nested loop with inner index scan. So, a query against a
> single table can never benefit from changing that setting.
That's flat out wrong. It does affect the cost estimate for plain
indexscan (and bitmap indexscan) plans.
regards, tom lane