Re: Slow standby snapshot

Simon Riggs <simon.riggs@enterprisedb.com> writes:
> I've cleaned up the comments and used a #define for the constant.
> IMHO this is ready for commit. I will add it to the next CF.

I looked at this a little.  It's a simple enough patch, and if it
solves the problem then I sure like it better than the previous
ideas in this thread.

However ... I tried to reproduce the original complaint, and
failed entirely.  I do see KnownAssignedXidsGetAndSetXmin
eating a bit of time in the standby backends, but it's under 1%
and doesn't seem to be rising over time.  Perhaps we've already
applied some optimization that ameliorates the problem?  But
I tested v13 as well as HEAD, and got the same results.

            regards, tom lane