Re: [GENERAL] large object does not exist after pg_migrator

Alvaro Herrera wrote:
> Bruce Momjian wrote:
> > Alvaro Herrera wrote:
> > > Bruce Momjian wrote:
> > > > Jamie Fox wrote:
> > >
> > > > > I can also see that the pg_largeobject table is different, in the pg_restore
> > > > > version the Rows (estimated) is 316286 and Rows (counted) is the same, in
> > > > > the pg_migrator version the Rows (counted) is only 180507.
> > >
> > > > Wow, I didn't test large objects specifically, and I am confused why
> > > > there would be a count discrepancy. I will need to do some research
> > > > unless someone else can guess about the cause.
> > >
> > > Maybe pg_largeobject is not getting frozen?
> >
> > That would explain the change in count, but I thought we froze
> > _everything_, and had to.
>
> After a quick chat with Bruce it was determined that we don't freeze
> anything (it would be horrid for downtime if we did so in pg_migrator;
> and it would be useless if ran anywhere else). What we do is migrate
> pg_clog from the old cluster to the new. So never mind that hypothesis.

FYI, we do freeze the new cluster that has only schema definitions, no
data.

> Bruce noticed that the pg_dump/pg_migrator combo is failing to restore
> pg_largeobject's relfrozenxid. We're not sure how this is causing the
> errors Jamie is seeing, because what I think should happen is that scans
> of the table should fail with failures to open pg_clog files
> such-and-such, but not missing tuples ...

Yea, I can fix that in PG 8.4.1, but that doesn't seem like the cause of
the missing rows. Alvaro and I are still investigating.

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

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