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
				('30', '31', '29', '15', '32', '25', '22')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('30', '31', '29', '15', '32', '25', '22')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=692889.61..692889.61 rows=3 width=20) (actual time=9708.128..9708.129 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=313757 read=12830
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52898.10..52898.11 rows=1 width=4) (actual time=482.932..482.932 rows=1 loops=1)
           Buffers: shared hit=35287 read=1054
           ->  Bitmap Heap Scan on customer customer_1  (cost=6645.42..51943.78 rows=381728 width=4) (actual time=82.289..402.347 rows=381913 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,31,29,15,32,25,22}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=35287 read=1054
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6549.99 rows=381728 width=0) (actual time=73.969..73.969 rows=381913 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{30,31,29,15,32,25,22}'::text[]))
                       Buffers: shared hit=10 read=1054
   ->  HashAggregate  (cost=639991.43..639991.47 rows=3 width=20) (actual time=9708.026..9708.027 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=313754 read=12830
         ->  Hash Anti Join  (cost=596629.06..639545.21 rows=59495 width=20) (actual time=9430.099..9690.437 rows=63841 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=313754 read=12830
               ->  Bitmap Heap Scan on customer  (cost=2909.36..41860.78 rows=139940 width=24) (actual time=533.515..685.437 rows=190982 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,31,29,15,32,25,22}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35157
                     Buffers: shared hit=70454 read=1593
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.37 rows=139940 width=0) (actual time=526.226..526.226 rows=190982 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,31,29,15,32,25,22}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35297 read=1593
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=8786.903..8786.903 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=243297 read=11237
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.019..4041.132 rows=15000000 loops=1)
                           Buffers: shared hit=243297 read=11237
 Planning time: 2.461 ms
 Execution time: 9712.218 ms
(34 rows)

COMMIT;
COMMIT