Re: Pg_upgrade and toast tables bug discovered

On Mon, Jul 14, 2014 at 09:40:33PM +0200, Andres Freund wrote:
> On 2014-07-11 09:55:34 -0400, Bruce Momjian wrote:
> > On Fri, Jul 11, 2014 at 09:48:06AM -0400, Bruce Momjian wrote:
> > > > Uh, why does this need to be in ALTER TABLE? Can't this be part of
> > > > table creation done by pg_dump?
> > >
> > > Uh, I think you need to read the thread. We have to delay the toast
> > > creation part so we don't use an oid that will later be required by
> > > another table from the old cluster. This has to be done after all
> > > tables have been created.
> > >
> > > We could have pg_dump spit out those ALTER lines at the end of the dump,
> > > but it seems simpler to do it in pg_upgrade.
> > >
> > > Even if we have pg_dump create all the tables that require pre-assigned
> > > TOAST oids first, then the other tables that _might_ need a TOAST table,
> > > those later tables might create a toast oid that matches a later
> > > non-TOAST-requiring table, so I don't think that fixes the problem.
> >
> > What would be nice is if I could mark just the tables that will need
> > toast tables created in that later phase (those tables that didn't have
> > a toast table in the old cluster, but need one in the new cluster).
> > However, I can't see where to store that or how to pass that back into
> > pg_upgrade. I don't see a logical place in pg_class to put it.
>
> This seems overengineered. Why not just do
> SELECT pg_upgrade.maintain_toast(oid) FROM pg_class WHERE relkind = 'r';
>
> and in maintain_toast() just call AlterTableCreateToastTable()?

I didn't think you could call into backend functions like that, and if I
did, it might break something in the future.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ Everyone has their own god. +