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 '1994-05-01'
	and o_orderdate < cast(date '1994-05-01' + 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=1152634.47..1152634.52 rows=20 width=175) (actual time=24643.792..24643.798 rows=20 loops=1)
   Buffers: shared hit=1038501 read=381109 dirtied=31 written=79
   ->  Sort  (cost=1152634.47..1154067.16 rows=573075 width=175) (actual time=24643.789..24643.793 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=1038501 read=381109 dirtied=31 written=79
         ->  HashAggregate  (cost=1131654.40..1137385.15 rows=573075 width=175) (actual time=24243.885..24490.102 rows=381821 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=1038498 read=381109 dirtied=31 written=79
               ->  Hash Join  (cost=351858.73..1117327.53 rows=573075 width=175) (actual time=4128.436..21757.771 rows=1150015 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1038498 read=381109 dirtied=31 written=79
                     ->  Hash Join  (cost=351857.17..1109446.19 rows=573075 width=153) (actual time=4128.384..21340.701 rows=1150015 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1038497 read=381109 dirtied=31 written=79
                           ->  Hash Join  (cost=282829.17..1031822.06 rows=573075 width=12) (actual time=2262.836..18667.083 rows=1150015 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=1003219 read=381109 dirtied=31 written=79
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..687506.67 rows=14868242 width=12) (actual time=0.083..12801.015 rows=14823489 loops=1)
                                       Buffers: shared hit=802342 read=351208 written=79
                                 ->  Hash  (cost=275565.72..275565.72 rows=581041 width=8) (actual time=2256.710..2256.710 rows=574590 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30637kB
                                       Buffers: shared hit=200877 read=29901 dirtied=31
                                       ->  Bitmap Heap Scan on orders  (cost=12316.11..275565.72 rows=581041 width=8) (actual time=325.424..2058.717 rows=574590 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                             Heap Blocks: exact=229203
                                             Buffers: shared hit=200877 read=29901 dirtied=31
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12170.84 rows=581041 width=0) (actual time=229.319..229.319 rows=576944 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                                   Buffers: shared read=1575
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1848.481..1848.481 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=145) (actual time=0.024..829.449 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.030..0.030 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=0.008..0.019 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 6.387 ms
 Execution time: 24677.306 ms
(42 rows)

COMMIT;
COMMIT