Re: Error on vacuum: xmin before relfrozenxid

Hi,

On 2018-05-22 21:43:01 +0200, Paolo Crosato wrote:
> > Could you report the result of
> > select ctid, xmin, xmax from pg_authid ;
> >
>
> This is the result:
>
> postgres=# select ctid, xmin, xmax from pg_authid ;

> (0,16) | 3031994631 | 0
> 16 | 6496 | 1 | 144 | 3031994631 | 0 | 0 | (0,16)
> | 32779 | 10507 | 32 | 1111111111000000 | 675851 |
> \x6e6167696f73000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000001000000ffffffff496d64356333633236616163636439616665346437383061396239613464663634653639

> postgres=# select relfrozenxid from pg_class where relname='pg_authid';
> relfrozenxid
> --------------
> 400011439

That tuple looks, to me, like it indeed shouldn't exist, given the
relfrozenxid. Decoding infomask (10507 / 0x290B), if I did it right,
shows:

HEAP_HASNULL
HEAP_HASVARWIDTH
HEAP_HASOID
HEAP_XMIN_COMMITTED
HEAP_XMAX_INVALID
HEAP_UPDATED

so it's not frozen. That suggests there's either a bug, or you had
corruption in your cluster.

Could you give a bit of "history" about that postgres instance? What
version of postgres was it run on earliest? Was it ever pg_upgraded?
Were there any OS crashes? Other hardware issues? Was the cluster ever
used with fsync=off or full_page_writes=off?

Greetings,

Andres Freund