Re: WIP: Avoid creation of the free space map for small tables

On Fri, Jan 25, 2019 at 1:03 AM John Naylor <john(dot)naylor(at)2ndquadrant(dot)com> wrote:
>
> On Wed, Jan 23, 2019 at 11:17 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > I think what doc means to say is
> > that it copies any unlinked files present in primary's new cluster
> > (which in your case will be data2).
>
> In that case, I'm still confused why that doc says, "Unfortunately,
> rsync needlessly copies files associated with temporary and unlogged
> tables because these files don't normally exist on standby servers."
> I fail to see why the primary's new cluster would have these if they
> weren't linked.
>

Why unlogged files won't be in primary's new cluster? After the
upgrade, they should be present in a new cluster if they were present
in the old cluster.

> And in the case we're discussing here, the skipped
> FSMs won't be on data2, so won't end up in standby/data2.
>

Right. I think we are safe with respect to rsync because I have seen
that we do rewrite the vm files in link mode and rsync will copy them
from primary's new cluster.

I think you can try to address my other comments on your pg_upgrade
patch. Once we agree on the code, we need to test below scenarios:
(a) upgrade from all supported versions to the latest version
(b) upgrade standby with and without using rsync.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com