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=1189482.73..1189482.78 rows=20 width=175) (actual time=57133.199..57133.208 rows=20 loops=1)
   Buffers: shared hit=725511 read=706516 dirtied=1283 written=17782
   ->  Sort  (cost=1189482.73..1190874.75 rows=556806 width=175) (actual time=57133.195..57133.202 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=725511 read=706516 dirtied=1283 written=17782
         ->  HashAggregate  (cost=1169098.26..1174666.32 rows=556806 width=175) (actual time=56653.822..56978.207 rows=354913 loops=1)
               Buffers: shared hit=725508 read=706516 dirtied=1283 written=17782
               ->  Hash Join  (cost=400698.34..1155178.11 rows=556806 width=175) (actual time=7278.909..52372.508 rows=941688 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=725508 read=706516 dirtied=1283 written=17782
                     ->  Hash Join  (cost=400696.78..1147520.47 rows=556806 width=153) (actual time=7278.857..51604.335 rows=941688 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=725507 read=706516 dirtied=1283 written=17782
                           ->  Merge Join  (cost=331668.78..1067356.35 rows=556806 width=12) (actual time=3876.052..45715.916 rows=941688 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=691000 read=705745 dirtied=1283 written=17782
                                 ->  Sort  (cost=331668.76..333088.07 rows=567724 width=8) (actual time=3875.533..4090.608 rows=562039 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50922kB
                                       Buffers: shared hit=229838 read=1628
                                       ->  Bitmap Heap Scan on orders  (cost=12333.16..277409.02 rows=567724 width=8) (actual time=682.319..2826.962 rows=562039 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                             Buffers: shared hit=229838 read=1628
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12191.23 rows=567724 width=0) (actual time=430.195..430.195 rows=568844 loops=1)
                                                   Index Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                                   Buffers: shared read=1628
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..690024.16 rows=14902700 width=12) (actual time=0.194..38011.335 rows=14822647 loops=1)
                                       Buffers: shared hit=461162 read=704117 dirtied=1283 written=17782
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3400.348..3400.348 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=34507 read=771
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.014..1244.063 rows=1500000 loops=1)
                                       Buffers: shared hit=34507 read=771
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.024..0.024 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=0.008..0.015 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 57204.034 ms
(40 rows)

COMMIT;
COMMIT