BEGIN;
BEGIN
EXPLAIN (ANALYZE, BUFFERS)
select
	cntrycode,
	count(*) as numcust,
	sum(c_acctbal) as totacctbal
from
	(
		select
			substr(c_phone, 1, 2) as cntrycode,
			c_acctbal
		from
			customer
		where
			substr(c_phone, 1, 2) in
				('25', '15', '11', '14', '27', '20', '18')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('25', '15', '11', '14', '27', '20', '18')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695925.15..695925.16 rows=3 width=20) (actual time=8627.246..8627.247 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=326693 read=904
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52929.93..52929.94 rows=1 width=4) (actual time=444.906..444.907 rows=1 loops=1)
           Buffers: shared hit=35741 read=599
           ->  Bitmap Heap Scan on customer customer_1  (cost=6652.15..51973.42 rows=382601 width=4) (actual time=98.578..366.496 rows=381735 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,15,11,14,27,20,18}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=35741 read=599
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6556.50 rows=382601 width=0) (actual time=89.151..89.151 rows=381735 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{25,15,11,14,27,20,18}'::text[]))
                       Buffers: shared hit=464 read=599
   ->  HashAggregate  (cost=642995.15..642995.19 rows=3 width=20) (actual time=8627.201..8627.202 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=326690 read=904
         ->  Hash Anti Join  (cost=598997.74..642552.26 rows=59052 width=20) (actual time=8345.969..8605.080 rows=63587 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=326690 read=904
               ->  Bitmap Heap Scan on customer  (cost=2912.80..41873.02 rows=140275 width=24) (actual time=513.085..660.128 rows=190548 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,15,11,14,27,20,18}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35158
                     Buffers: shared hit=71139 read=904
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2877.73 rows=140275 width=0) (actual time=503.529..503.529 rows=190548 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,15,11,14,27,20,18}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35981 read=904
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=7751.004..7751.004 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=255548
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.020..3464.769 rows=15015000 loops=1)
                           Buffers: shared hit=255548
 Planning time: 2.215 ms
 Execution time: 8638.357 ms
(34 rows)

COMMIT;
COMMIT