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 '1994-10-01'
	and o_orderdate < cast(date '1994-10-01' + 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=1196251.05..1196251.10 rows=20 width=175) (actual time=27179.352..27179.361 rows=20 loops=1)
   Buffers: shared hit=626812 read=795165 dirtied=822 written=534
   ->  Sort  (cost=1196251.05..1197671.54 rows=568197 width=175) (actual time=27179.348..27179.354 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=626812 read=795165 dirtied=822 written=534
         ->  HashAggregate  (cost=1175449.56..1181131.53 rows=568197 width=175) (actual time=26599.727..27019.478 rows=381726 loops=1)
               Buffers: shared hit=626809 read=795165 dirtied=822 written=534
               ->  Hash Join  (cost=401668.91..1161244.63 rows=568197 width=175) (actual time=4701.178..24022.829 rows=1149938 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=626809 read=795165 dirtied=822 written=534
                     ->  Hash Join  (cost=401667.35..1153430.36 rows=568197 width=153) (actual time=4701.136..23546.398 rows=1149938 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=626808 read=795165 dirtied=822 written=534
                           ->  Merge Join  (cost=332639.35..1073038.42 rows=568197 width=12) (actual time=2942.120..19738.851 rows=1149938 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=593241 read=793454 dirtied=822 written=534
                                 ->  Sort  (cost=332639.31..334076.01 rows=574677 width=8) (actual time=2941.855..3078.218 rows=574230 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51494kB
                                       Buffers: shared hit=166992 read=65977 dirtied=237
                                       ->  Bitmap Heap Scan on orders  (cost=12484.43..277664.59 rows=574677 width=8) (actual time=327.376..2677.793 rows=574230 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-10-01'::date) AND (o_orderdate < '1995-01-01'::date))
                                             Buffers: shared hit=166992 read=65977 dirtied=237
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12340.76 rows=574677 width=0) (actual time=242.290..242.290 rows=581825 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-10-01'::date) AND (o_orderdate < '1995-01-01'::date))
                                                   Buffers: shared read=1665
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..694286.39 rows=15023570 width=12) (actual time=0.125..14382.990 rows=14808149 loops=1)
                                       Buffers: shared hit=426249 read=727477 dirtied=585 written=534
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1756.628..1756.628 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=33567 read=1711
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.007..713.858 rows=1500000 loops=1)
                                       Buffers: shared hit=33567 read=1711
                     ->  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: 2kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.008..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 27257.586 ms
(40 rows)

COMMIT;
COMMIT