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 '1993-07-01'
	and o_orderdate < cast(date '1993-07-01' + 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=1194324.12..1194324.17 rows=20 width=175) (actual time=78750.116..78750.123 rows=20 loops=1)
   Buffers: shared hit=991003 read=435139 dirtied=829 written=632
   ->  Sort  (cost=1194324.12..1195755.70 rows=572633 width=175) (actual time=78750.111..78750.116 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=991003 read=435139 dirtied=829 written=632
         ->  HashAggregate  (cost=1173360.23..1179086.56 rows=572633 width=175) (actual time=78196.785..78577.777 rows=381644 loops=1)
               Buffers: shared hit=991000 read=435139 dirtied=829 written=632
               ->  Hash Join  (cost=400743.14..1159044.41 rows=572633 width=175) (actual time=10380.051..73892.171 rows=1147150 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=991000 read=435139 dirtied=829 written=632
                     ->  Hash Join  (cost=400741.58..1151169.14 rows=572633 width=153) (actual time=10379.997..72912.426 rows=1147150 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=990999 read=435139 dirtied=829 written=632
                           ->  Merge Join  (cost=331713.58..1070688.48 rows=572633 width=12) (actual time=7372.529..67166.841 rows=1147150 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=955722 read=435138 dirtied=829 written=632
                                 ->  Sort  (cost=331713.57..333156.55 rows=577192 width=8) (actual time=7372.131..7597.143 rows=573813 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51474kB
                                       Buffers: shared hit=229546 read=1939 dirtied=17 written=145
                                       ->  Bitmap Heap Scan on orders  (cost=12510.19..276480.07 rows=577192 width=8) (actual time=728.285..7054.143 rows=573813 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-07-01'::date) AND (o_orderdate < '1993-10-01'::date))
                                             Buffers: shared hit=229546 read=1939 dirtied=17 written=145
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12365.90 rows=577192 width=0) (actual time=603.882..603.882 rows=578778 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-07-01'::date) AND (o_orderdate < '1993-10-01'::date))
                                                   Buffers: shared hit=114 read=1538 written=124
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..692860.39 rows=15001571 width=12) (actual time=0.346..55686.690 rows=14808204 loops=1)
                                       Buffers: shared hit=726176 read=433199 dirtied=812 written=487
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3005.729..3005.729 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35277 read=1
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.016..1716.473 rows=1500000 loops=1)
                                       Buffers: shared hit=35277 read=1
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.028..0.028 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=0.008..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 78799.539 ms
(40 rows)

COMMIT;
COMMIT