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 '1993-12-01'
	and o_orderdate < cast(date '1993-12-01' + 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=1192871.90..1192871.95 rows=20 width=176) (actual time=26415.609..26415.616 rows=20 loops=1)
   Buffers: shared hit=498227 read=926747 dirtied=2812 written=987
   ->  Sort  (cost=1192871.90..1194289.70 rows=567122 width=176) (actual time=26415.606..26415.610 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=498227 read=926747 dirtied=2812 written=987
         ->  HashAggregate  (cost=1172109.76..1177780.98 rows=567122 width=176) (actual time=25873.574..26258.775 rows=374996 loops=1)
               Buffers: shared hit=498224 read=926747 dirtied=2812 written=987
               ->  Hash Join  (cost=400368.05..1157931.71 rows=567122 width=176) (actual time=3893.329..23492.716 rows=1121333 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=498224 read=926747 dirtied=2812 written=987
                     ->  Hash Join  (cost=400366.49..1150132.22 rows=567122 width=154) (actual time=3893.284..23031.335 rows=1121333 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=498223 read=926747 dirtied=2812 written=987
                           ->  Merge Join  (cost=331338.49..1069761.78 rows=567122 width=12) (actual time=1951.248..19135.026 rows=1121333 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=462945 read=926747 dirtied=2812 written=987
                                 ->  Sort  (cost=331338.47..332770.07 rows=572641 width=8) (actual time=1951.110..2089.304 rows=561012 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50874kB
                                       Buffers: shared hit=228518 read=1801 dirtied=446
                                       ->  Bitmap Heap Scan on orders  (cost=12435.55..276573.17 rows=572641 width=8) (actual time=224.287..1756.760 rows=561012 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-12-01'::date) AND (o_orderdate < '1994-03-01'::date))
                                             Buffers: shared hit=228518 read=1801 dirtied=446
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12292.39 rows=572641 width=0) (actual time=157.582..157.582 rows=565493 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-12-01'::date) AND (o_orderdate < '1994-03-01'::date))
                                                   Buffers: shared hit=2 read=1617
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..692416.15 rows=14989100 width=12) (actual time=0.100..14773.164 rows=14822822 loops=1)
                                       Buffers: shared hit=234427 read=924946 dirtied=2366 written=987
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1940.134..1940.134 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=0.012..827.788 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.025..0.025 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..0.014 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 26468.715 ms
(40 rows)

COMMIT;
COMMIT