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 '1994-04-01'
	and o_orderdate < cast(date '1994-04-01' + 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=1191186.73..1191186.78 rows=20 width=175) (actual time=29180.342..29180.351 rows=20 loops=1)
   Buffers: shared hit=761796 read=664016 dirtied=112 written=90427
   ->  Sort  (cost=1191186.73..1192608.17 rows=568575 width=175) (actual time=29180.338..29180.344 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=761796 read=664016 dirtied=112 written=90427
         ->  HashAggregate  (cost=1170371.40..1176057.15 rows=568575 width=175) (actual time=28623.375..29004.256 rows=379038 loops=1)
               Buffers: shared hit=761793 read=664016 dirtied=112 written=90427
               ->  Hash Join  (cost=400921.71..1156157.03 rows=568575 width=175) (actual time=3757.812..25891.810 rows=1138041 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=761793 read=664016 dirtied=112 written=90427
                     ->  Hash Join  (cost=400920.14..1148337.56 rows=568575 width=153) (actual time=3757.773..25319.164 rows=1138041 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=761792 read=664016 dirtied=112 written=90427
                           ->  Merge Join  (cost=331892.14..1067938.06 rows=568575 width=12) (actual time=2155.399..21688.417 rows=1138041 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=726517 read=664013 dirtied=112 written=90427
                                 ->  Sort  (cost=331884.59..333325.99 rows=576560 width=8) (actual time=2155.266..2306.893 rows=568635 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51231kB
                                       Buffers: shared hit=229522 read=1635
                                       ->  Bitmap Heap Scan on orders  (cost=12519.72..276716.12 rows=576560 width=8) (actual time=431.543..1954.712 rows=568635 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                             Buffers: shared hit=229522 read=1635
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12375.58 rows=576560 width=0) (actual time=312.226..312.226 rows=573228 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                                   Buffers: shared hit=2 read=1635
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..690171.56 rows=14925352 width=12) (actual time=0.108..16660.374 rows=14822803 loops=1)
                                       Buffers: shared hit=496995 read=662378 dirtied=112 written=90427
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1600.285..1600.285 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35275 read=3
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.014..643.661 rows=1500000 loops=1)
                                       Buffers: shared hit=35275 read=3
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.021..0.021 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=0.007..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 29226.158 ms
(40 rows)

COMMIT;
COMMIT