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
				('13', '22', '15', '19', '20', '14', '33')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('13', '22', '15', '19', '20', '14', '33')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691148.60..691148.60 rows=3 width=20) (actual time=8672.539..8672.540 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=323975 read=1593
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52901.54..52901.55 rows=1 width=4) (actual time=453.435..453.436 rows=1 loops=1)
           Buffers: shared hit=35288 read=1057
           ->  Bitmap Heap Scan on customer customer_1  (cost=6646.12..51946.98 rows=381823 width=4) (actual time=84.821..378.682 rows=382565 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,22,15,19,20,14,33}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35288 read=1057
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6550.67 rows=381823 width=0) (actual time=76.558..76.558 rows=382565 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{13,22,15,19,20,14,33}'::text[]))
                       Buffers: shared hit=10 read=1057
   ->  HashAggregate  (cost=638246.98..638247.03 rows=3 width=20) (actual time=8672.439..8672.441 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=323972 read=1593
         ->  Hash Anti Join  (cost=594268.86..637804.92 rows=58941 width=20) (actual time=8438.062..8654.668 rows=63560 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323972 read=1593
               ->  Bitmap Heap Scan on customer  (cost=2909.72..41861.93 rows=139970 width=24) (actual time=505.366..631.227 rows=190973 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,22,15,19,20,14,33}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35149
                     Buffers: shared hit=70447 read=1593
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.72 rows=139970 width=0) (actual time=498.113..498.113 rows=190973 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,22,15,19,20,14,33}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35298 read=1593
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=7887.240..7887.240 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=253522
                     ->  Seq Scan on orders  (cost=0.00..403671.84 rows=15014984 width=4) (actual time=0.033..4219.717 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Planning time: 3.818 ms
 Execution time: 8676.480 ms
(34 rows)

COMMIT;
COMMIT