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 '1994-06-01'
	and o_orderdate < cast(date '1994-06-01' + 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=1186306.47..1186306.52 rows=20 width=175) (actual time=38772.289..38772.298 rows=20 loops=1)
   Buffers: shared hit=679926 read=743556 dirtied=250 written=289
   ->  Sort  (cost=1186306.47..1187709.87 rows=561361 width=175) (actual time=38772.284..38772.289 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=679926 read=743556 dirtied=250 written=289
         ->  HashAggregate  (cost=1165755.25..1171368.86 rows=561361 width=175) (actual time=38203.872..38568.445 rows=382131 loops=1)
               Buffers: shared hit=679923 read=743556 dirtied=250 written=289
               ->  Hash Join  (cost=398398.90..1151721.22 rows=561361 width=175) (actual time=5762.234..34549.416 rows=1149840 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=679923 read=743556 dirtied=250 written=289
                     ->  Hash Join  (cost=398397.33..1144000.94 rows=561361 width=153) (actual time=5762.172..33763.747 rows=1149840 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=679922 read=743556 dirtied=250 written=289
                           ->  Merge Join  (cost=329369.33..1063745.72 rows=561361 width=12) (actual time=2962.014..28208.141 rows=1149840 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=644741 read=743459 dirtied=250 written=289
                                 ->  Sort  (cost=329369.33..330789.09 rows=567901 width=8) (actual time=2961.867..3158.477 rows=574847 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51522kB
                                       Buffers: shared hit=221916 read=8872 dirtied=135
                                       ->  Bitmap Heap Scan on orders  (cost=12038.89..275091.40 rows=567901 width=8) (actual time=609.313..2665.624 rows=574847 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-06-01'::date) AND (o_orderdate < '1994-09-01'::date))
                                             Buffers: shared hit=221916 read=8872 dirtied=135
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11896.91 rows=567901 width=0) (actual time=477.524..477.524 rows=577200 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-06-01'::date) AND (o_orderdate < '1994-09-01'::date))
                                                   Buffers: shared hit=2 read=1577
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..688672.15 rows=14901329 width=12) (actual time=0.125..21706.137 rows=14823475 loops=1)
                                       Buffers: shared hit=422825 read=734587 dirtied=115 written=289
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2797.577..2797.577 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35181 read=97
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.019..1004.053 rows=1500000 loops=1)
                                       Buffers: shared hit=35181 read=97
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.035..0.035 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=0.009..0.022 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 38859.693 ms
(40 rows)

COMMIT;
COMMIT