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
				('20', '18', '10', '27', '17', '25', '31')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('20', '18', '10', '27', '17', '25', '31')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=698193.97..698193.98 rows=3 width=20) (actual time=9775.714..9775.715 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=234161 read=94469 written=2
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52877.78..52877.79 rows=1 width=4) (actual time=679.549..679.549 rows=1 loops=1)
           Buffers: shared hit=16347 read=19993
           ->  Bitmap Heap Scan on customer customer_1  (cost=6641.08..51924.84 rows=381172 width=4) (actual time=97.773..607.437 rows=381568 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,18,10,27,17,25,31}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=16347 read=19993
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6545.79 rows=381172 width=0) (actual time=88.814..88.814 rows=381568 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{20,18,10,27,17,25,31}'::text[]))
                       Buffers: shared hit=7 read=1055
   ->  HashAggregate  (cost=645316.12..645316.16 rows=3 width=20) (actual time=9775.659..9775.661 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=234158 read=94469 written=2
         ->  Hash Anti Join  (cost=601352.77..644874.82 rows=58840 width=20) (actual time=9146.213..9753.281 rows=63775 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=234158 read=94469 written=2
               ->  Bitmap Heap Scan on customer  (cost=2907.28..41853.24 rows=139732 width=24) (actual time=739.627..1235.018 rows=190643 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,18,10,27,17,25,31}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35178
                     Buffers: shared hit=16543 read=55521
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.34 rows=139732 width=0) (actual time=731.129..731.129 rows=190643 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,18,10,27,17,25,31}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=16357 read=20529
               ->  Hash  (cost=408509.11..408509.11 rows=15194911 width=4) (actual time=8325.172..8325.172 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=217612 read=38948 written=2
                     ->  Seq Scan on orders  (cost=0.00..408509.11 rows=15194911 width=4) (actual time=0.021..4310.517 rows=15015000 loops=1)
                           Buffers: shared hit=217612 read=38948 written=2
 Planning time: 3.136 ms
 Execution time: 9779.947 ms
(34 rows)

COMMIT;
COMMIT