On Tue, 2 Jul 2002 pgsql-bugs@postgresql.org wrote:
> John Liu (johnl@emrx.com) reports a bug with a severity of 2
> The lower the number the more severe it is.
>
> Short Description
> NULLs order by bug in 7.2.1
>
> Long Description
> select date_fld from my_table order by date_fld desc;
>
> The above query put NULLs on top of normal values
> in stead of bottom, this is not the case in 7.1.3.
I think this was the bug fix. I read the applicable
section of the spec as saying that NULLs are treated
as either all greater or all less than non-null values
for order by, so if the nulls come at the end of an asc
order by, they come at the front of the desc one.