On 2020-Jul-14, Andres Freund wrote:
> Hi,
>
> On 2020-07-14 13:20:25 -0400, Alvaro Herrera wrote:
> > Just having the block number is already a tremendous step forward; with
> > that you can ask the customer to set a pageinspect dump of tuple
> > headers, and then the problem is obvious. Now if you want to add block
> > number to that, by all means do so.
>
> offset number I assume?
Eh, yeah, that.
> > One useful thing to do is to mark a tuple frozen unconditionally if it's
> > marked hinted XMIN_COMMITTED; no need to consult pg_clog in that case.
> > The attached (for 9.6) does that; IIRC it would have helped in a couple
> > of cases.
>
> I think it might also have hidden corruption in at least one case where
> we subsequently fixed a bug (and helped detect at least one unfixed
> bug). That should only be possible if either required clog has been
> removed, or if relfrozenxid/datfrozenxid are corrupt, right?
Yes, that's precisely the reason I never submitted it :-)
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services