title: function to calculate aggregate sum count in postgresql
body: <p>Is there a function that calculates the total count of the complete month like below?  I am not sure if postgres.  I am looking for the grand total value.</p>
  
  <pre><code>2012-08=# select date_trunc('day', time), count(distinct column) from table_name group by 1 order by 1;
  
       date_trunc      | count 
  ---------------------+-------
   2012-08-01 00:00:00 |    22
   2012-08-02 00:00:00 |    34
   2012-08-03 00:00:00 |    25
   2012-08-04 00:00:00 |    30
   2012-08-05 00:00:00 |    27
   2012-08-06 00:00:00 |    31
   2012-08-07 00:00:00 |    23
   2012-08-08 00:00:00 |    28
   2012-08-09 00:00:00 |    28
   2012-08-10 00:00:00 |    28
   2012-08-11 00:00:00 |    24
   2012-08-12 00:00:00 |    36
   2012-08-13 00:00:00 |    28
   2012-08-14 00:00:00 |    23
   2012-08-15 00:00:00 |    23
   2012-08-16 00:00:00 |    30
   2012-08-17 00:00:00 |    20
   2012-08-18 00:00:00 |    30
   2012-08-19 00:00:00 |    20
   2012-08-20 00:00:00 |    24
   2012-08-21 00:00:00 |    20
   2012-08-22 00:00:00 |    17
   2012-08-23 00:00:00 |    23
   2012-08-24 00:00:00 |    25
   2012-08-25 00:00:00 |    35
   2012-08-26 00:00:00 |    18
   2012-08-27 00:00:00 |    16
   2012-08-28 00:00:00 |    11
   2012-08-29 00:00:00 |    22
   2012-08-30 00:00:00 |    26
   2012-08-31 00:00:00 |    17
  (31 rows)
  --------------------------------
        Total          |    12345
  </code></pre>