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 '1994-12-01'
	and o_orderdate < cast(date '1994-12-01' + 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=1153394.30..1153394.35 rows=20 width=176) (actual time=26514.318..26514.324 rows=20 loops=1)
   Buffers: shared hit=903917 read=521890 dirtied=1992 written=1157
   ->  Sort  (cost=1153394.30..1154766.64 rows=548937 width=176) (actual time=26514.314..26514.319 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=903917 read=521890 dirtied=1992 written=1157
         ->  HashAggregate  (cost=1133297.92..1138787.29 rows=548937 width=176) (actual time=26061.886..26372.064 rows=370965 loops=1)
               Group Key: customer.c_custkey, customer.c_name, customer.c_acctbal, customer.c_phone, nation.n_name, customer.c_address, customer.c_comment
               Buffers: shared hit=903914 read=521890 dirtied=1992 written=1157
               ->  Hash Join  (cost=352070.26..1119574.49 rows=548937 width=176) (actual time=4039.578..23750.953 rows=1078860 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=903914 read=521890 dirtied=1992 written=1157
                     ->  Hash Join  (cost=352068.69..1112025.04 rows=548937 width=154) (actual time=4039.540..23343.048 rows=1078860 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=903913 read=521890 dirtied=1992 written=1157
                           ->  Hash Join  (cost=283040.69..1034762.99 rows=548937 width=12) (actual time=2554.883..20760.454 rows=1078860 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=868635 read=521890 dirtied=1992 written=1157
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..690269.79 rows=14923620 width=12) (actual time=0.059..13148.250 rows=14807964 loops=1)
                                       Buffers: shared hit=710890 read=449049 dirtied=1907 written=596
                                 ->  Hash  (cost=276079.06..276079.06 rows=556896 width=8) (actual time=2550.321..2550.321 rows=561185 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30114kB
                                       Buffers: shared hit=157745 read=72841 dirtied=85 written=561
                                       ->  Bitmap Heap Scan on orders  (cost=12092.62..276079.06 rows=556896 width=8) (actual time=292.522..2351.716 rows=561185 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                             Heap Blocks: exact=228964
                                             Buffers: shared hit=157745 read=72841 dirtied=85 written=561
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11953.39 rows=556896 width=0) (actual time=212.495..212.495 rows=566854 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                                   Buffers: shared hit=97 read=1525 written=17
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1477.007..1477.007 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.014..651.200 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.022..0.022 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.007..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.421 ms
 Execution time: 26539.518 ms
(42 rows)

COMMIT;
COMMIT