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 '1995-01-01'
	and o_orderdate < cast(date '1995-01-01' + 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=1150693.72..1150693.77 rows=20 width=175) (actual time=23879.393..23879.400 rows=20 loops=1)
   Buffers: shared hit=699910 read=719983 written=284
   ->  Sort  (cost=1150693.72..1152064.24 rows=548206 width=175) (actual time=23879.389..23879.395 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=699910 read=719983 written=284
         ->  HashAggregate  (cost=1130624.10..1136106.16 rows=548206 width=175) (actual time=23307.978..23730.495 rows=354869 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=699907 read=719983 written=284
               ->  Hash Join  (cost=351344.78..1116918.95 rows=548206 width=175) (actual time=4278.164..21250.577 rows=941654 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=699907 read=719983 written=284
                     ->  Hash Join  (cost=351343.21..1109379.55 rows=548206 width=153) (actual time=4278.118..20916.918 rows=941654 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=699906 read=719983 written=284
                           ->  Hash Join  (cost=282315.21..1032128.46 rows=548206 width=12) (actual time=2597.776..18504.108 rows=941654 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=672669 read=711942 written=284
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..688504.24 rows=14887303 width=12) (actual time=0.057..12345.383 rows=14822937 loops=1)
                                       Buffers: shared hit=548174 read=606375 written=284
                                 ->  Hash  (cost=275362.02..275362.02 rows=556221 width=8) (actual time=2591.251..2591.251 rows=562049 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30148kB
                                       Buffers: shared hit=124495 read=105567
                                       ->  Bitmap Heap Scan on orders  (cost=11977.70..275362.02 rows=556221 width=8) (actual time=292.242..2384.564 rows=562049 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                             Heap Blocks: exact=228478
                                             Buffers: shared hit=124495 read=105567
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11838.64 rows=556221 width=0) (actual time=211.062..211.062 rows=565453 loops=1)
                                                   Index Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                                   Buffers: shared read=1584
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1663.234..1663.234 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=27237 read=8041
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.018..689.507 rows=1500000 loops=1)
                                       Buffers: shared hit=27237 read=8041
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.028..0.028 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=0.006..0.014 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.594 ms
 Execution time: 23915.851 ms
(42 rows)

COMMIT;
COMMIT