BEGIN;
BEGIN
EXPLAIN (ANALYZE, BUFFERS)
select
	supp_nation,
	cust_nation,
	l_year,
	sum(volume) as revenue
from
	(
		select
			n1.n_name as supp_nation,
			n2.n_name as cust_nation,
			extract(year from l_shipdate) as l_year,
			l_extendedprice * (1 - l_discount) as volume
		from
			supplier,
			lineitem,
			orders,
			customer,
			nation n1,
			nation n2
		where
			s_suppkey = l_suppkey
			and o_orderkey = l_orderkey
			and c_custkey = o_custkey
			and s_nationkey = n1.n_nationkey
			and c_nationkey = n2.n_nationkey
			and (
				(n1.n_name = 'CANADA' and n2.n_name = 'ROMANIA')
				or (n1.n_name = 'ROMANIA' and n2.n_name = 'CANADA')
			)
			and l_shipdate between date '1995-01-01' and date '1996-12-31'
	) as shipping
group by
	supp_nation,
	cust_nation,
	l_year
order by
	supp_nation,
	cust_nation,
	l_year;
                                                                                       QUERY PLAN                                                                                        
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=2001891.89..2001899.56 rows=3068 width=64) (actual time=21427.252..21427.253 rows=4 loops=1)
   Sort Key: n1.n_name, n2.n_name, (date_part('year'::text, (lineitem.l_shipdate)::timestamp without time zone))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=5045731 read=466090 written=7
   ->  HashAggregate  (cost=2001668.19..2001714.21 rows=3068 width=64) (actual time=21427.136..21427.140 rows=4 loops=1)
         Group Key: n1.n_name, n2.n_name, date_part('year'::text, (lineitem.l_shipdate)::timestamp without time zone)
         Buffers: shared hit=5045723 read=466090 written=7
         ->  Hash Join  (cost=62340.37..2000756.01 rows=60812 width=64) (actual time=937.186..21335.350 rows=58590 loops=1)
               Hash Cond: (lineitem.l_suppkey = supplier.s_suppkey)
               Join Filter: (((n1.n_name = 'CANADA'::bpchar) AND (n2.n_name = 'ROMANIA'::bpchar)) OR ((n1.n_name = 'ROMANIA'::bpchar) AND (n2.n_name = 'CANADA'::bpchar)))
               Rows Removed by Join Filter: 58472
               Buffers: shared hit=5045723 read=466090 written=7
               ->  Nested Loop  (cost=58604.97..1988898.77 rows=1461268 width=42) (actual time=862.638..20612.994 rows=1453239 loops=1)
                     Buffers: shared hit=5043540 read=466090 written=7
                     ->  Hash Join  (cost=58604.40..531536.45 rows=1203596 width=30) (actual time=862.466..10042.525 rows=1195648 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=216593 read=72714 written=5
                           ->  Seq Scan on orders  (cost=0.00..404477.52 rows=15044952 width=8) (actual time=0.015..3712.300 rows=15015000 loops=1)
                                 Buffers: shared hit=192298 read=61730 written=5
                           ->  Hash  (cost=57104.40..57104.40 rows=120000 width=30) (actual time=861.485..861.485 rows=119897 loops=1)
                                 Buckets: 131072  Batches: 1  Memory Usage: 8284kB
                                 Buffers: shared hit=24295 read=10984
                                 ->  Hash Join  (cost=1.40..57104.40 rows=120000 width=30) (actual time=0.075..812.591 rows=119897 loops=1)
                                       Hash Cond: (customer.c_nationkey = n2.n_nationkey)
                                       Buffers: shared hit=24295 read=10984
                                       ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=8) (actual time=0.009..554.784 rows=1500000 loops=1)
                                             Buffers: shared hit=24294 read=10984
                                       ->  Hash  (cost=1.38..1.38 rows=2 width=30) (actual time=0.038..0.038 rows=2 loops=1)
                                             Buckets: 1024  Batches: 1  Memory Usage: 9kB
                                             Buffers: shared hit=1
                                             ->  Seq Scan on nation n2  (cost=0.00..1.38 rows=2 width=30) (actual time=0.020..0.028 rows=2 loops=1)
                                                   Filter: ((n_name = 'ROMANIA'::bpchar) OR (n_name = 'CANADA'::bpchar))
                                                   Rows Removed by Filter: 23
                                                   Buffers: shared hit=1
                     ->  Index Scan using lineitem_l_orderkey_l_linenumber_l_shipdate_idx on lineitem  (cost=0.56..1.16 rows=5 width=20) (actual time=0.007..0.008 rows=1 loops=1195648)
                           Index Cond: ((l_orderkey = orders.o_orderkey) AND (l_shipdate >= '1995-01-01'::date) AND (l_shipdate <= '1996-12-31'::date))
                           Buffers: shared hit=4826947 read=393376 written=2
               ->  Hash  (cost=3635.40..3635.40 rows=8000 width=30) (actual time=74.440..74.440 rows=8083 loops=1)
                     Buckets: 8192  Batches: 1  Memory Usage: 554kB
                     Buffers: shared hit=2180
                     ->  Hash Join  (cost=1.40..3635.40 rows=8000 width=30) (actual time=0.067..69.675 rows=8083 loops=1)
                           Hash Cond: (supplier.s_nationkey = n1.n_nationkey)
                           Buffers: shared hit=2180
                           ->  Seq Scan on supplier  (cost=0.00..3179.00 rows=100000 width=8) (actual time=0.016..42.996 rows=100000 loops=1)
                                 Buffers: shared hit=2179
                           ->  Hash  (cost=1.38..1.38 rows=2 width=30) (actual time=0.027..0.027 rows=2 loops=1)
                                 Buckets: 1024  Batches: 1  Memory Usage: 9kB
                                 Buffers: shared hit=1
                                 ->  Seq Scan on nation n1  (cost=0.00..1.38 rows=2 width=30) (actual time=0.012..0.022 rows=2 loops=1)
                                       Filter: ((n_name = 'CANADA'::bpchar) OR (n_name = 'ROMANIA'::bpchar))
                                       Rows Removed by Filter: 23
                                       Buffers: shared hit=1
 Planning time: 7.161 ms
 Execution time: 21427.861 ms
(54 rows)

COMMIT;
COMMIT