Re: Getting rid of duplicate tables.

Jared Carr <jared@89glass.com> writes:
>  Item   2 -- Length:  148  Offset: 6860 (0x1acc)  Flags: USED
>   XID: min (46034931)  CMIN|XMAX: 2  CMAX|XVAC: 0
>   Block Id: 27  linp Index: 2   Attributes: 23   Size: 28
>   infomask: 0x2910 (HASOID|XMIN_COMMITTED|XMAX_INVALID|UPDATED)

>  Item  43 -- Length:  148  Offset: 8044 (0x1f6c)  Flags: USED
>   XID: min (8051642)  CMIN|XMAX: 46034931  CMAX|XVAC: 2
>   Block Id: 27  linp Index: 2   Attributes: 23   Size: 28
>   infomask: 0x2910 (HASOID|XMIN_COMMITTED|XMAX_INVALID|UPDATED)

Well, there's the smoking gun ... somebody marked (27,2) as
XMIN_COMMITTED, showing that they thought 46034931 was committed, while
someone else marked (27,43) as XMAX_INVALID, showing that they thought
46034931 was aborted.  So we have some kind of very-infrequent
breakage in transaction commit-state lookup.  Or a hardware problem,
but I suspect we are looking at a bug.

Could you check out what pg_clog has for transaction 46034931?
This would be pg_clog/002B (which dates your problem to Dec 29 BTW),
byte at offset 39BFC hex or 236540 decimal.  I forget which way the
bits run within the byte but will look it up if you can get me the
value of that byte.

I'm off to take a real close look at what was done to the pg_clog code
during the 7.4 cycle ...

            regards, tom lane