Re:

Wade Klaver <archeron(at)wavefire(dot)com> writes:
> dropsites=# vacuum full analyze;
> WARNING: Rel pg_type: TID 12/46: InsertTransactionInProgress 27217603 - can't
> shrink relation
> WARNING: Rel pg_type: TID 12/47: InsertTransactionInProgress 27217603 - can't
> shrink relation
> WARNING: Rel pg_attribute: TID 152/1: InsertTransactionInProgress 27217603 -
> can't shrink relation
> WARNING: Rel pg_attribute: TID 152/2: InsertTransactionInProgress 27217603 -
> can't shrink relation
> ...
> ...
> And so on. The source code says "this should never happen".

7.4 has downgraded those messages to NOTICEs, and says

/*
* This should not happen, since we hold exclusive
* lock on the relation; shouldn't we raise an error?
* (Actually, it can happen in system catalogs, since
* we tend to release write lock before commit there.)
*/

If you saw it on anything besides a system catalog, then I'm interested,
but otherwise not to worry.

BTW, you really should update to 7.3.4.

regards, tom lane