EXPLAIN select 100.00 * sum(case when p_type like 'PROMO%' then l_extendedprice * (1 - l_discount) else 0 end) / sum(l_extendedprice * (1 - l_discount)) as promo_revenue from lineitem, part where l_partkey = p_partkey and l_shipdate >= date '1994-04-01' and l_shipdate < date '1994-04-01' + interval '1 month';
                                                                 QUERY PLAN                                                                 
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 Aggregate  (cost=1167121.22..1167121.24 rows=1 width=29)
   ->  Hash Join  (cost=114114.36..1155535.66 rows=662032 width=29)
         Hash Cond: (lineitem.l_partkey = part.p_partkey)
         ->  Bitmap Heap Scan on lineitem  (cost=14816.64..1020400.70 rows=698154 width=12)
               Recheck Cond: ((l_shipdate >= '1994-04-01'::date) AND (l_shipdate < '1994-05-01 00:00:00'::timestamp without time zone))
               ->  Bitmap Index Scan on i_l_shipdate  (cost=0.00..14642.11 rows=698154 width=0)
                     Index Cond: ((l_shipdate >= '1994-04-01'::date) AND (l_shipdate < '1994-05-01 00:00:00'::timestamp without time zone))
         ->  Hash  (cost=60626.43..60626.43 rows=1999943 width=25)
               ->  Seq Scan on part  (cost=0.00..60626.43 rows=1999943 width=25)
(9 rows)