On 10/21/21 4:06 PM, Robert Haas wrote:
On Thu, Oct 21, 2021 at 9:09 AM Joe Conway <m...@joeconway.com> wrote:
I think you are exactly correct. People seem to understand that with a
predicate it is harder, but they expect
select count(*) from foo;
to be nearly instantaneous, and they don't really need it to be exact.
The stock answer for that has been to do
select reltuples from pg_class
where relname = 'foo';
But that is unsatisfying because the problem is often with some
benchmark or another that cannot be changed.
I would also expect it to almost always give the wrong answer.
That is a grossly overstated position. When I have looked, it is often
not that terribly far off. And for many use cases that I have heard of
at least, quite adequate.
Joe
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