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
				('18', '26', '23', '32', '19', '10', '17')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '26', '23', '32', '19', '10', '17')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691310.62..691310.63 rows=3 width=20) (actual time=8492.480..8492.481 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=324002 read=1592
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52980.92..52980.93 rows=1 width=4) (actual time=470.880..470.880 rows=1 loops=1)
           Buffers: shared hit=35287 read=1056
           ->  Bitmap Heap Scan on customer customer_1  (cost=6681.90..52022.57 rows=383340 width=4) (actual time=87.566..395.725 rows=382133 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,26,23,32,19,10,17}'::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..6586.06 rows=383340 width=0) (actual time=79.312..79.312 rows=382133 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,26,23,32,19,10,17}'::text[]))
                       Buffers: shared hit=9 read=1056
   ->  HashAggregate  (cost=638329.62..638329.66 rows=3 width=20) (actual time=8492.376..8492.378 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=323999 read=1592
         ->  Hash Anti Join  (cost=594304.03..637886.89 rows=59031 width=20) (actual time=8266.687..8474.776 rows=63488 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323999 read=1592
               ->  Bitmap Heap Scan on customer  (cost=2944.89..41915.53 rows=140672 width=24) (actual time=523.302..640.735 rows=190823 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,26,23,32,19,10,17}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35177
                     Buffers: shared hit=70474 read=1592
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2909.72 rows=140672 width=0) (actual time=516.092..516.092 rows=190823 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,26,23,32,19,10,17}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35297 read=1592
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=7697.853..7697.853 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=0.024..3993.364 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Planning time: 3.923 ms
 Execution time: 8496.672 ms
(34 rows)

COMMIT;
COMMIT