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
				('34', '20', '13', '18', '21', '29', '12')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('34', '20', '13', '18', '21', '29', '12')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693552.86..693552.87 rows=3 width=20) (actual time=11140.542..11140.543 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=252133 read=74458 written=22
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52919.56..52919.57 rows=1 width=4) (actual time=542.471..542.471 rows=1 loops=1)
           Buffers: shared hit=35163 read=1180
           ->  Bitmap Heap Scan on customer customer_1  (cost=6649.98..51963.77 rows=382316 width=4) (actual time=105.698..465.702 rows=382165 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,20,13,18,21,29,12}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35163 read=1180
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6554.40 rows=382316 width=0) (actual time=96.339..96.339 rows=382165 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{34,20,13,18,21,29,12}'::text[]))
                       Buffers: shared hit=10 read=1055
   ->  HashAggregate  (cost=640633.22..640633.26 rows=3 width=20) (actual time=11140.485..11140.487 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=252130 read=74458 written=22
         ->  Hash Anti Join  (cost=596632.29..640192.37 rows=58780 width=20) (actual time=10388.594..11115.522 rows=63866 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=252130 read=74458 written=22
               ->  Bitmap Heap Scan on customer  (cost=2912.59..41872.23 rows=140253 width=24) (actual time=606.004..1181.662 rows=190856 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,20,13,18,21,29,12}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35160
                     Buffers: shared hit=35175 read=36876 written=16
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2877.52 rows=140253 width=0) (actual time=597.364..597.364 rows=190856 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,20,13,18,21,29,12}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35173 read=1718
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=9668.288..9668.288 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=216952 read=37582 written=6
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.025..4903.187 rows=15015000 loops=1)
                           Buffers: shared hit=216952 read=37582 written=6
 Planning time: 3.353 ms
 Execution time: 11157.667 ms
(34 rows)

COMMIT;
COMMIT