GroupAggregate  (cost=364639.91..387330.55 rows=206279 width=13) (actual time=11319.768..14212.760 rows=99996 loops=1)
  Group Key: _user, _session_id
  ->  Sort  (cost=364639.91..369796.87 rows=2062785 width=13) (actual time=11319.747..13626.636 rows=2062858 loops=1)
        Sort Key: _user, _session_id
        Sort Method: external merge  Disk: 52400kB
        ->  Seq Scan on view_page  (cost=0.00..113037.85 rows=2062785 width=13) (actual time=0.007..897.178 rows=2062858 loops=1)
Planning time: 0.189 ms
Execution time: 14239.138 ms

EXPLAIN ANALYZE SELECT count(*)
 FROM
   "demo_ecommerce"."view_page"
 GROUP BY "_user", "_session_id"