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=1190552.99..1190553.04 rows=20 width=176) (actual time=38412.131..38412.137 rows=20 loops=1)
   Buffers: shared hit=1167067 read=257941 dirtied=1132 written=31
   ->  Sort  (cost=1190552.99..1191980.65 rows=571063 width=176) (actual time=38412.128..38412.130 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=1167067 read=257941 dirtied=1132 written=31
         ->  HashAggregate  (cost=1169646.58..1175357.21 rows=571063 width=176) (actual time=37808.034..38197.498 rows=382099 loops=1)
               Buffers: shared hit=1167064 read=257941 dirtied=1132 written=31
               ->  Hash Join  (cost=400523.97..1155370.00 rows=571063 width=176) (actual time=6767.749..34351.446 rows=1149798 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1167064 read=257941 dirtied=1132 written=31
                     ->  Hash Join  (cost=400522.40..1147516.32 rows=571063 width=154) (actual time=6767.712..33622.243 rows=1149798 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1167063 read=257941 dirtied=1132 written=31
                           ->  Merge Join  (cost=331494.40..1067067.06 rows=571063 width=12) (actual time=4669.600..29296.955 rows=1149798 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1131785 read=257941 dirtied=1132 written=31
                                 ->  Sort  (cost=331494.38..332939.70 rows=578127 width=8) (actual time=4669.458..4926.352 rows=574833 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51522kB
                                       Buffers: shared hit=229435 read=1868
                                       ->  Bitmap Heap Scan on orders  (cost=12451.76..276164.66 rows=578127 width=8) (actual time=524.071..3030.440 rows=574833 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-06-01'::date) AND (o_orderdate < '1994-09-01'::date))
                                             Buffers: shared hit=229435 read=1868
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12307.22 rows=578127 width=0) (actual time=311.228..311.228 rows=578357 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-06-01'::date) AND (o_orderdate < '1994-09-01'::date))
                                                   Buffers: shared read=1638
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..689670.47 rows=14920376 width=12) (actual time=0.118..20932.592 rows=14822923 loops=1)
                                       Buffers: shared hit=902350 read=256073 dirtied=1132 written=31
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2096.034..2096.034 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.013..1015.667 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.017..0.017 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..0.010 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 38455.682 ms
(40 rows)

COMMIT;
COMMIT