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
				('31', '20', '26', '23', '22', '11', '33')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('31', '20', '26', '23', '22', '11', '33')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695852.63..695852.64 rows=3 width=20) (actual time=9460.916..9460.916 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=237140 read=90457 written=1
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52887.94..52887.95 rows=1 width=4) (actual time=685.368..685.368 rows=1 loops=1)
           Buffers: shared hit=11 read=36330
           ->  Bitmap Heap Scan on customer customer_1  (cost=6643.25..51934.31 rows=381450 width=4) (actual time=96.891..613.685 rows=381401 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,20,26,23,22,11,33}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=11 read=36330
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6547.89 rows=381450 width=0) (actual time=88.021..88.021 rows=381401 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{31,20,26,23,22,11,33}'::text[]))
                       Buffers: shared hit=9 read=1055
   ->  HashAggregate  (cost=642964.62..642964.66 rows=3 width=20) (actual time=9460.872..9460.874 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=237137 read=90457 written=1
         ->  Hash Anti Join  (cost=598993.43..642523.06 rows=58874 width=20) (actual time=9177.344..9438.570 rows=63449 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=237137 read=90457 written=1
               ->  Bitmap Heap Scan on customer  (cost=2908.50..41857.64 rows=139853 width=24) (actual time=753.834..903.098 rows=190845 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,20,26,23,22,11,33}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35155
                     Buffers: shared hit=35177 read=36866
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2873.53 rows=139853 width=0) (actual time=744.809..744.809 rows=190845 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,20,26,23,22,11,33}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=22 read=36866
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=8345.907..8345.907 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=201957 read=53591 written=1
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.016..3900.399 rows=15015000 loops=1)
                           Buffers: shared hit=201957 read=53591 written=1
 Planning time: 2.505 ms
 Execution time: 9472.577 ms
(34 rows)

COMMIT;
COMMIT