BUG #7786: select from view is computing columns not selected

The following bug has been logged on the website:

Bug reference: 7786
Logged by: Douglas Toltzman
Email address: doug(at)oakstreetsoftware(dot)com
PostgreSQL version: 9.2.2
Operating system: Linux CentOS
Description:

in the interest of simplicity, I've got a view that calls a stored procedure
to compute a value ...

create view testv as select tt.field1, tt.intfield, compute_val(tt.field1)
AS compute1 from tt;

If compute_val() selects sum(intfield) from the testv view, compute_val() is
called again when selecting records from testv (even though compute1 was not
selected), resulting in infinite recursion (stack overflow).

In retrospect, I realize this may have been a bad thing to do, but it worked
in version 8.1.x. I recently upgraded to 9.2.2 and I had to create a 2nd
view that didn't include the computed values, so I could use that view in
the stored procedures.

It seems like a performance problem to compute all columns in a view when
selecting only specific columns. I've already fixed my stack overflow, so
I'll let you decide if this is a bug or a feature.

If you're interested in reproducing this and you don't understand my
description, I'd be happy to provide a test case.