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
				('21', '19', '22', '13', '24', '33', '12')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('21', '19', '22', '13', '24', '33', '12')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693557.96..693557.97 rows=3 width=20) (actual time=8799.827..8799.827 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=250809 read=75787
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52928.79..52928.80 rows=1 width=4) (actual time=412.256..412.257 rows=1 loops=1)
           Buffers: shared hit=35287 read=1056
           ->  Bitmap Heap Scan on customer customer_1  (cost=6651.93..51972.36 rows=382569 width=4) (actual time=102.267..341.117 rows=381905 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,19,22,13,24,33,12}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35287 read=1056
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6556.29 rows=382569 width=0) (actual time=93.338..93.338 rows=381905 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{21,19,22,13,24,33,12}'::text[]))
                       Buffers: shared hit=9 read=1056
   ->  HashAggregate  (cost=640629.09..640629.13 rows=3 width=20) (actual time=8799.780..8799.780 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=250806 read=75787
         ->  Hash Anti Join  (cost=596632.43..640186.24 rows=59047 width=20) (actual time=8578.319..8779.175 rows=63383 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=250806 read=75787
               ->  Bitmap Heap Scan on customer  (cost=2912.73..41872.63 rows=140263 width=24) (actual time=477.926..575.301 rows=190546 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,19,22,13,24,33,12}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35167
                     Buffers: shared hit=70463 read=1593
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2877.66 rows=140263 width=0) (actual time=469.256..469.256 rows=190546 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,19,22,13,24,33,12}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35296 read=1593
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=8055.136..8055.136 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=180340 read=74194
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.011..4054.694 rows=15015000 loops=1)
                           Buffers: shared hit=180340 read=74194
 Planning time: 2.892 ms
 Execution time: 8804.104 ms
(34 rows)

COMMIT;
COMMIT