On Tue, May 24, 2016 at 8:50 AM, David G. Johnston
<david.g.johnston@xxxxxxxxx> wrote:
> SELECT x, sum(i), sum(sum(i)) OVER (PARTITION BY x) FROM ( VALUES (a,1),
> (a,2), (b,3) ) val (x,i) GROUP BY x
> yields
> a, 3, 6
> b, 3, 6
Thank you for this enlightening explanation! I was, however, very
confused from this specific bit, so I tested it and indeed there must
have been a typo:
postgres=# SELECT x, sum(i), sum(sum(i)) OVER (PARTITION BY x) FROM
(VALUES ('a', 1), ('a', 2), ('b', 3)) val (x,i) GROUP BY x;
x | sum | sum
---+-----+-----
a | 3 | 3
b | 3 | 3
(2 rows)
Yes, that was me being careless. The partition in the window makes the sum(sum(i)) evaluate to 3
David J.
