The "Allow easy display of usernames in a group (pg_hba.conf uses groups

The "Allow easy display of usernames in a group (pg_hba.conf uses groups
now)" item on the open items, and subsequent plpgsql function I sent in,
made me realize it was too hard to get the upper and lower bound of an
array. The attached creates two functions that I think will be very
useful when combined with the ability of plpgsql to return sets.

array_lower(array, dim_num)
- and -
array_upper(array, dim_num)

They return the value (as an int) of the upper and lower bound of the
requested dim in the provided array.

Joe Conway