Re: pg_attribute, pg_class, pg_depend grow huge in count and size with multiple tenants.

Hi,

On Fri, May 8, 2020 at 3:31 AM Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>
wrote:

> On Thu, 2020-05-07 at 18:17 -0300, Avinash Kumar wrote:
> > > The nice thing about separate databases is that it is easy to scale
> > > horizontally.
> >
> > Agreed. But, how about autovacuum ? Workers shift from DB to DB and 500
> clusters
> > means you may have to have a lot of manual vacuuming in place as well.
>
> Just set "autovacuum_max_workers" higher.
>
No, that wouldn't help. If you just increase autovacuum_max_workers, the
total cost limit of autovacuum_vacuum_cost_limit (or vacuum_cost_limit) is
shared by so many workers and it further delays autovacuum per each worker.
Instead you need to increase autovacuum_vacuum_cost_limit as well when you
increase the number of workers. But, if you do that and also increase
workers, well, you would easily reach the limitations of the disk. I am not
sure it is anywhere advised to have 20 autovacuum_max_workers unless i have
a disk with lots of IOPS and with very tiny tables across all the
databases.

>
> Yours,
> Laurenz Albe
> --
> Cybertec | https://www.cybertec-postgresql.com
>
>

--
Regards,
Avinash Vallarapu