The following bug has been logged online:

Bug reference: 2203
Logged by: Robert Hostetter
Email address: robert (AT) newcovsoft (DOT) com
PostgreSQL version: 8.1
Operating system: CentOS 4.1
Description: Group by, suggested "feature"
Details:

I'm sure this will be considered a missing feature and not a bug, I know I
would. We are converting from MySQL to PostgreSQL, which is a huge project.
But one minor irritation we've noticed is the group by handling in
PostgreSQL. If you group by a primary key for a table, you still have to
include all the other columns you SELECT from that row, even though its
guaranteed uniuqe because its a primary key. I understand requiring the
other columns when you aren't guaranteed uniqueness, but in cases of a group
by on a unique column you shouldn't need to include the rows, its
repetitive, and makes porting harder for no reason. Also on a similar note,
you can't group by any column you don't select.

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Robert Hostetter wrote:
Yes, this feature request is known as supporting functional
dependencies. We're aware of it.

Sure you can.

--
Peter Eisentraut
http://developer.postgresql.org/~petere/

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