Re: max_connections

ok, running too many connections without recycling has an overhead.
no wonder pgbouncer is all over as a sidecar :)

In case anyone is interested, this blog is a great read.
Analyzing the Limits of Connection Scalability in Postgres - Microsoft Tech
Community
<https://techcommunity.microsoft.com/t5/azure-database-for-postgresql/analyzing-the-limits-of-connection-scalability-in-postgres/ba-p/1757266>

<https://techcommunity.microsoft.com/t5/azure-database-for-postgresql/analyzing-the-limits-of-connection-scalability-in-postgres/ba-p/1757266>

On Sun, 30 May 2021 at 20:19, Vijaykumar Jain <
vijaykumarjain(dot)github(at)gmail(dot)com> wrote:

> I have a two dumb questions.
>
> 1)
> I know the max_connections value change requires a restart.
>
> I also read a thread, which says why it is the case, assuming it still
> holds true.
>
> Jean Arnaud <Jean(dot)Arnaud(at)inrialpes(dot)fr> writes:
> > I'm looking for a way to change the "max_connections" parameter without
> > restarting the PostGreSQL database.
>
> There is none. That's one of the parameters that determines shared
> memory array sizes, and we can't change those on-the-fly.
>
> regards, tom lane
>
> Does that mean, if I set max_connections to 1000 users, but only intend to
> use 10 at max (via conn limit per role settings), what would be the perf
> difference compared to max_connections = 100 , but still using only 10 at
> max.
>
> 2)
> can i for test purposes.compile src with a xid max value to 2^16 etc ?
> like with uint16
>
> Basically, I was trying to simulate xid wraparound, by creating an open
> transaction and an inactive replication slot, and then running a huge
> parallel loops to bump txid_current() to see what happens at 2B crossover.
> it takes forever on my slow laptop.
> I do not see these in test scenarios, or could not find any.
>
> as always, ignore if not relevant, or already discussed.
> I am preparing for interviews, hence asking myself dumb questions :)
>
> --
> Thanks,
> Vijay
> Mumbai, India
>

--
Thanks,
Vijay
Mumbai, India