Re: found xmin from before relfrozenxid on pg_catalog.pg_authid

On Mon, Mar 19, 2018 at 1:55 PM, Jeremy Finzel <finzelj(at)gmail(dot)com> wrote:
> @Peter :
>
> staging=# SELECT * FROM page_header(get_raw_page('pg_authid', 7));
> lsn | checksum | flags | lower | upper | special | pagesize |
> version | prune_xid
> ----------------+----------+-------+-------+-------+---------+----------+---------+-----------
> 262B4/10FDC478 | 0 | 1 | 304 | 2224 | 8192 | 8192 |
> 4 | 0
> (1 row)

Thanks.

That looks normal. I wonder if the contents of that page looks
consistent with the rest of the table following manual inspection,
though. I recently saw system catalog corruption on a 9.5 instance
where an entirely different relation's page ended up in pg_attribute
and pg_depend. They were actually pristine index pages from an
application index. I still have no idea why this happened.

This is very much a guess, but it can't hurt to check if the contents
of the tuples themselves are actually sane by inspecting them with
"SELECT * FROM pg_authid". heap_page_items() doesn't actually care
about the shape of the tuples in the page, so this might have been
missed.

--
Peter Geoghegan