The following bug has been logged online:

Bug reference: 2477
Logged by: John Rylander
Email address: rylander@prolexia.com
PostgreSQL version: 8.1.4
Operating system: Windows XP
Description: Aggregate Integer divisors incorrectly yield
integer-type quotient
Details:

When for some reason I did a sum/count instead of an avg, the result was
always an integer (either 0 or 1):

Sum(
Case when Sign(Delta)=Sign(AvgDelta) then
1
else
0
) / Count(*) as HitRate;

If I use "/ Count(*)::float4", or use Avg instead of Sum/Count, it works
fine.

Yet another maddening PostgreSQL bug/idiosyncrasy. Time for this boy to go
to Oracle (not because of this, but because of the function->transaction
problem, such that a function that has nested loops that create myriad
temporary analytical tables necessarily runs out of disk space; if it
weren't for the mandatory and completely counterproductive implicit
transaction, it'd take very little space and a lot less time).

---------------------------(end of broadcast)---------------------------
TIP 2: Don't 'kill -9' the postmaster