Re: Hmmm... why does CPU-intensive pl/pgsql code parallelise so badly when queries parallelise fine? Anyone else seen this?

On 2015-07-08 15:38:24 -0700, Craig James wrote:
> From my admittedly naive point of view, it's hard to see why any of this
> matters. I have functions that do purely CPU-intensive mathematical
> calculations ... you could imagine something like is_prime(N) that
> determines if N is a prime number. I have eight clients that connect to
> eight backends. Each client issues an SQL command like, "select
> is_prime(N)" where N is a simple number.

I mostly replied to Merlin's general point (additionally in the context of
plpgsql).

But I have a hard time seing that postgres would be the bottleneck for a
is_prime() function (or something with similar characteristics) that's
written in C where the average runtime is more than, say, a couple
thousand cyles.  I'd like to see a profile of that.

Andres