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 '1994-10-01'
	and o_orderdate < cast(date '1994-10-01' + 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=1147934.43..1147934.48 rows=20 width=175) (actual time=30524.334..30524.340 rows=20 loops=1)
   Buffers: shared hit=819808 read=590126 written=5652
   ->  Sort  (cost=1147934.43..1149338.22 rows=561515 width=175) (actual time=30524.330..30524.332 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=819808 read=590126 written=5652
         ->  HashAggregate  (cost=1127377.57..1132992.72 rows=561515 width=175) (actual time=30106.185..30375.656 rows=381877 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=819805 read=590126 written=5652
               ->  Hash Join  (cost=350533.30..1113339.69 rows=561515 width=175) (actual time=4759.371..27198.921 rows=1150269 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=819805 read=590126 written=5652
                     ->  Hash Join  (cost=350531.74..1105617.30 rows=561515 width=153) (actual time=4759.312..26743.049 rows=1150269 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=819804 read=590126 written=5652
                           ->  Hash Join  (cost=281503.74..1028166.57 rows=561515 width=12) (actual time=2557.597..23377.209 rows=1150269 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=819801 read=554851 written=5652
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..685458.53 rows=14823891 width=12) (actual time=0.065..14936.225 rows=14808183 loops=1)
                                       Buffers: shared hit=651270 read=493019 written=5652
                                 ->  Hash  (cost=274386.79..274386.79 rows=569321 width=8) (actual time=2549.656..2549.656 rows=574384 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30629kB
                                       Buffers: shared hit=168531 read=61832
                                       ->  Bitmap Heap Scan on orders  (cost=12071.98..274386.79 rows=569321 width=8) (actual time=368.177..2342.724 rows=574384 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-10-01'::date) AND (o_orderdate < '1995-01-01'::date))
                                             Heap Blocks: exact=228791
                                             Buffers: shared hit=168531 read=61832
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11929.64 rows=569321 width=0) (actual time=264.408..264.408 rows=575549 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-10-01'::date) AND (o_orderdate < '1995-01-01'::date))
                                                   Buffers: shared read=1572
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2181.521..2181.521 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=3 read=35275
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.023..1059.555 rows=1500000 loops=1)
                                       Buffers: shared hit=3 read=35275
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.032..0.032 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=0.009..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 8.374 ms
 Execution time: 30549.184 ms
(42 rows)

COMMIT;
COMMIT