DISCTINCT and literals - Unable to identify an ordering operator

Hi Folks,

We're new to postgres and we have a question. We're using 7.1.x on
Linux and we've had to change all of our code with "SELECT DISTINCT"
and character literals to work around what looks like an SQL bug.
Here's an example of the problem:

template1=# SELECT DISTINCT 'foo';
ERROR: Unable to identify an ordering operator '<' for type 'unknown'
Use an explicit ordering operator or modify the query
template1=# SELECT DISTINCT CAST ('foo' AS CHAR(3));
?column?
----------
foo
(1 row)

template1=#

Notice that we have to use a CAST to avoid the bug, and it doesn't
seem necessary - all other RDBMSs we use don't require this. Please
tell us: Are there plans for fixing this? It's a pain to have to
change all our queries... Thanks!

matt
mcornell(at)spamcop(dot)net