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 '1993-04-01'
	and o_orderdate < cast(date '1993-04-01' + 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=1149000.18..1149000.23 rows=20 width=175) (actual time=31967.860..31967.870 rows=20 loops=1)
   Buffers: shared hit=921526 read=491903 written=2263
   ->  Sort  (cost=1149000.18..1150405.37 rows=562073 width=175) (actual time=31967.856..31967.860 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=921526 read=491903 written=2263
         ->  HashAggregate  (cost=1128422.89..1134043.62 rows=562073 width=175) (actual time=31268.238..31724.358 rows=378841 loops=1)
               Group Key: customer.c_custkey, customer.c_name, customer.c_acctbal, customer.c_phone, nation.n_name, customer.c_address, customer.c_comment
               Buffers: shared hit=921523 read=491903 written=2263
               ->  Hash Join  (cost=350807.70..1114371.07 rows=562073 width=175) (actual time=4436.418..24976.178 rows=1136720 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=921523 read=491903 written=2263
                     ->  Hash Join  (cost=350806.14..1106641.00 rows=562073 width=153) (actual time=4436.377..24501.198 rows=1136720 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=921522 read=491903 written=2263
                           ->  Hash Join  (cost=281778.14..1029181.91 rows=562073 width=12) (actual time=2785.004..21921.648 rows=1136720 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=899757 read=478390 written=2263
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..686138.58 rows=14838637 width=12) (actual time=0.070..14738.138 rows=14823192 loops=1)
                                       Buffers: shared hit=737082 read=411585 written=2251
                                 ->  Hash  (cost=274654.11..274654.11 rows=569888 width=8) (actual time=2778.863..2778.863 rows=568355 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30394kB
                                       Buffers: shared hit=162675 read=66805 written=12
                                       ->  Bitmap Heap Scan on orders  (cost=12077.79..274654.11 rows=569888 width=8) (actual time=299.378..2577.510 rows=568355 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-04-01'::date) AND (o_orderdate < '1993-07-01'::date))
                                             Heap Blocks: exact=227926
                                             Buffers: shared hit=162675 read=66805 written=12
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11935.32 rows=569888 width=0) (actual time=216.864..216.864 rows=569447 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-04-01'::date) AND (o_orderdate < '1993-07-01'::date))
                                                   Buffers: shared hit=1 read=1553
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1643.945..1643.945 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=21765 read=13513
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.015..804.863 rows=1500000 loops=1)
                                       Buffers: shared hit=21765 read=13513
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.023..0.023 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.007..0.010 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.317 ms
 Execution time: 31999.721 ms
(42 rows)

COMMIT;
COMMIT