BEGIN;
BEGIN
EXPLAIN (ANALYZE, BUFFERS)
select
	c_custkey,
	c_name,
	sum(l_extendedprice * (1 - l_discount)) as revenue,
	c_acctbal,
	n_name,
	c_address,
	c_phone,
	c_comment
from
	customer,
	orders,
	lineitem,
	nation
where
	c_custkey = o_custkey
	and l_orderkey = o_orderkey
	and o_orderdate >= date '1993-07-01'
	and o_orderdate < cast(date '1993-07-01' + interval '3 month' as date)
	and l_returnflag = 'R'
	and c_nationkey = n_nationkey
group by
	c_custkey,
	c_name,
	c_acctbal,
	c_phone,
	n_name,
	c_address,
	c_comment
order by
	revenue desc
LIMIT 20;
                                                                                                QUERY PLAN                                                                                                 
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=1184325.86..1184325.91 rows=20 width=175) (actual time=33973.801..33973.809 rows=20 loops=1)
   Buffers: shared hit=1132890 read=276804 dirtied=343 written=2121
   ->  Sort  (cost=1184325.86..1185748.30 rows=568978 width=175) (actual time=33973.796..33973.799 rows=20 loops=1)
         Sort Key: (sum((lineitem.l_extendedprice * (1::double precision - lineitem.l_discount))))
         Sort Method: top-N heapsort  Memory: 30kB
         Buffers: shared hit=1132890 read=276804 dirtied=343 written=2121
         ->  HashAggregate  (cost=1163495.78..1169185.56 rows=568978 width=175) (actual time=33407.058..33796.104 rows=381524 loops=1)
               Buffers: shared hit=1132887 read=276804 dirtied=343 written=2121
               ->  Hash Join  (cost=398466.33..1149271.33 rows=568978 width=175) (actual time=9191.720..28384.785 rows=1146932 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1132887 read=276804 dirtied=343 written=2121
                     ->  Hash Join  (cost=398464.76..1141446.32 rows=568978 width=153) (actual time=9191.681..27708.841 rows=1146932 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1132886 read=276804 dirtied=343 written=2121
                           ->  Merge Join  (cost=329436.76..1061038.76 rows=568978 width=12) (actual time=6742.989..23109.734 rows=1146932 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1098146 read=276266 dirtied=343 written=2121
                                 ->  Sort  (cost=329436.76..330875.79 rows=575610 width=8) (actual time=6742.762..6912.182 rows=573713 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51469kB
                                       Buffers: shared hit=4 read=229791 dirtied=229
                                       ->  Bitmap Heap Scan on orders  (cost=12209.90..274366.05 rows=575610 width=8) (actual time=407.855..6389.028 rows=573713 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-07-01'::date) AND (o_orderdate < '1993-10-01'::date))
                                             Buffers: shared hit=4 read=229791 dirtied=229
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12066.00 rows=575610 width=0) (actual time=250.879..250.879 rows=574235 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-07-01'::date) AND (o_orderdate < '1993-10-01'::date))
                                                   Buffers: shared hit=2 read=1570
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..685931.42 rows=14841974 width=12) (actual time=0.123..13140.226 rows=14808322 loops=1)
                                       Buffers: shared hit=1098142 read=46475 dirtied=114 written=2121
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2446.961..2446.961 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=34740 read=538
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.012..1077.433 rows=1500000 loops=1)
                                       Buffers: shared hit=34740 read=538
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.020..0.020 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 2kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.006..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 34032.823 ms
(40 rows)

COMMIT;
COMMIT