I wrote:
> Andres Freund <andres@anarazel.de> writes:
>> I am pretty unhappy about that, I think the test and rules are just about
>> incomprehensible. I wonder if we ought to instead just redefine float8 to be
>> be aligned to 8 bytes, leaving double alone.
> I thought about that, but it seemed like there'd be nothing stopping
> people from declaring a catalog column as "double" rather than
> "float8" and thus falling into the trap anyway. I suppose we could
> put a check for that into Catalog.pm, though.
No, scratch that: the real objection is that we can't do that unless
we are willing to break pg_upgrade on AIX. The catalogs can't have
different alignment rules than user tables do. Now, maybe we're
willing to go there, but it's not a pleasant prospect.
regards, tom lane