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 '1994-03-01'
	and o_orderdate < cast(date '1994-03-01' + 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=1155383.33..1155383.38 rows=20 width=175) (actual time=23662.349..23662.355 rows=20 loops=1)
   Buffers: shared hit=817068 read=604841 written=505
   ->  Sort  (cost=1155383.33..1156793.15 rows=563926 width=175) (actual time=23662.348..23662.352 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=817068 read=604841 written=505
         ->  HashAggregate  (cost=1134738.20..1140377.46 rows=563926 width=175) (actual time=23295.364..23524.442 rows=381382 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=817065 read=604841 written=505
               ->  Hash Join  (cost=352391.59..1120640.05 rows=563926 width=175) (actual time=3954.703..21180.335 rows=1148761 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=817065 read=604841 written=505
                     ->  Hash Join  (cost=352390.02..1112884.51 rows=563926 width=153) (actual time=3954.668..20783.885 rows=1148761 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=817064 read=604841 written=505
                           ->  Hash Join  (cost=283362.02..1035397.62 rows=563926 width=12) (actual time=2209.731..18235.012 rows=1148761 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=795350 read=591277 written=505
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..690386.01 rows=14936204 width=12) (actual time=0.064..12491.597 rows=14823054 loops=1)
                                       Buffers: shared hit=602714 read=552306 written=479
                                 ->  Hash  (cost=276225.78..276225.78 rows=570865 width=8) (actual time=2202.929..2202.929 rows=573687 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30602kB
                                       Buffers: shared hit=192636 read=38971 written=26
                                       ->  Bitmap Heap Scan on orders  (cost=12367.80..276225.78 rows=570865 width=8) (actual time=318.558..2000.702 rows=573687 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                             Heap Blocks: exact=229962
                                             Buffers: shared hit=192636 read=38971 written=26
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12225.09 rows=570865 width=0) (actual time=232.709..232.709 rows=577659 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                                   Buffers: shared read=1645 written=1
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1731.679..1731.679 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=21714 read=13564
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.021..749.437 rows=1500000 loops=1)
                                       Buffers: shared hit=21714 read=13564
                     ->  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: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.006..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.315 ms
 Execution time: 23683.430 ms
(42 rows)

COMMIT;
COMMIT