tti=# explain select call_type, flow, SUM(minutes) AS total_minutes FROM pstn_cdr WHERE calldate >= '2006-07-01 00:00:00' AND calldate < '2006-08-01 00:00:00' GROUP BY call_type, flow;
QUERY PLAN
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HashAggregate (cost=49500.45..49502.95 rows=200 width=25)
-> Bitmap Heap Scan on pstn_cdr (cost=183.31..49352.57 rows=19718 width=25)
Recheck Cond: ((calldate >= '2006-07-01 00:00:00'::timestamp without time zone) AND (calldate < '2006-08-01 00:00:00'::timestamp without time zone))
-> Bitmap Index Scan on calldate_idx (cost=0.00..183.31 rows=19718 width=0)
Index Cond: ((calldate >= '2006-07-01 00:00:00'::timestamp without time zone) AND (calldate < '2006-08-01 00:00:00'::timestamp without time zone))
(5 rows)