Re: Get sum of sums

"David G. Johnston" <david.g.johnston@xxxxxxxxx> · Tue, 3 May 2016 13:08:42 -0700

On Tue, May 3, 2016 at 12:57 PM, Victor Yegorov <vyegorov@xxxxxxxxx> wrote:
2016-05-03 22:48 GMT+03:00 Steve Clark <sclark@xxxxxxxxxxxxx>:
select ip_dst as "Receiver" ,sum(bytes) as "RX Bytes" from acct_v9
      where stamp_inserted >= '2016-04-26' and stamp_inserted <=
      '2016-04-30' and tag=246 group by ip_dst  order by "RX Bytes" desc
      limit 10;

SELECT ip_dst AS "Receiver",
    sum(bytes) AS "RX Bytes",
    sum(sum(bytes)) OVER () AS "Grand Total"
  FROM acct_v9
 WHERE stamp_inserted BETWEEN '2016-04-26' AND '2016-04-30'
    AND tag=246
 GROUP BY ip_dst
 ORDER BY "RX Bytes" DESC
 LIMIT 10;

I am not sure bout the LIMIT though, I hope window function will be calculated after the LIMIT is applied.

You will be disappointed, then.  Limit will not impact the values within records, it only impacts which records are returned to the client.  You have to move the limit into a subquery if you want it to apply before the window function computation.

SELECT i, sum(sum(i)) OVER ()
FROM generate_series(1, 10) gs (i)
GROUP BY i
ORDER BY i
LIMIT 5;

P.S. 
8.4 is long out of support - though fortunately you have access to window functions so the suggested approach can be made to work.