Anomaly with SUM().

I've noticed that the SUM() seems to overflow under some situations.

The only difference is the order that the data is retrived from the
database.



accounting=# select  sum(amount)  from transactions, chart WHERE
account=chart.id;
         sum
---------------------
5.6843418860808e-14
(1 row)

accounting=# select  sum(amount)  from transactions, chart WHERE
account=chart.id AND amount=amount;
sum
-----
   0
(1 row)




More Info:
accounting=# select  amount  from transactions, chart WHERE
account=chart.id;
amount
--------
    -75
  21.13
    -83
   2.13
    -83
     21
     50
     50
   2.26
   -166
     99
   2.21
    -83
   -100
     39
     25
    -70
  -0.02
     45
  -0.05
  -0.05
  -0.04
  -0.04
     70
     75
     83
     83
    166
     83
    100
   0.02
   0.05
   0.05
   0.04
   0.04
    -21
    -45
-21.13
  -2.13
  -2.26
  -2.21
    -50
    -50
    -99
    -39
    -25
(46 rows)

accounting=# select  amount  from transactions, chart WHERE
account=chart.id AND amount=amount;
amount
--------
    -70
     70
    -75
     75
  -0.02
   0.02
    -45
     45
-21.13
  21.13
  -0.05
   0.05
    -83
     83
  -0.05
   0.05
  -2.13
   2.13
    -83
     83
    -21
     21
    -50
     50
  -0.04
   0.04
    -50
     50
  -2.26
   2.26
   -166
    166
    -99
     99
  -0.04
   0.04
  -2.21
   2.21
    -83
     83
   -100
    100
    -39
     39
    -25
     25
(46 rows)