Re: Support getrandom() for pg_strong_random() source - Mailing list pgsql-hackers

On Wed, Jul 30, 2025 at 02:03:53PM -0700, Jacob Champion wrote:
> On Wed, Jul 30, 2025 at 12:58 PM Peter Eisentraut <peter@eisentraut.org> wrote:
> > I imagine a "get entropy" operation could be very slow or even blocking,
> > whereas a random number generator might just have to do some arithmetic
> > starting from the previous seed state.
>
> Agreed -- it could absolutely be slower, but if it's not slower in
> practice in a user's environment, is there a problem with using it as
> the basis for pg_strong_random()? That doesn't seem "wrong" to me; it
> just seems like a tradeoff that would take investigation.

Yeah, we need to be careful here.  Having a blocking or less efficient
operation would be bad for the UUID generation, especially in
INSERT-only workloads and there are a lot of such things these days
that also want to maintain some uniqueness of the data gathered across
multiple nodes.  I'm questioning whether the UUID generation could
become a bottleneck if we are not careful, showing high in profiles.
--
Michael