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
				('24', '26', '19', '28', '17', '10', '27')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('24', '26', '19', '28', '17', '10', '27')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693034.09..693034.10 rows=3 width=20) (actual time=10383.816..10383.816 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=50397 read=276192
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52977.03..52977.04 rows=1 width=4) (actual time=648.935..648.935 rows=1 loops=1)
           Buffers: shared hit=11 read=36329
           ->  Bitmap Heap Scan on customer customer_1  (cost=6681.08..52018.95 rows=383233 width=4) (actual time=72.124..583.918 rows=381277 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,26,19,28,17,10,27}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=11 read=36329
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6585.27 rows=383233 width=0) (actual time=64.970..64.970 rows=381277 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{24,26,19,28,17,10,27}'::text[]))
                       Buffers: shared hit=9 read=1053
   ->  HashAggregate  (cost=640056.98..640057.03 rows=3 width=20) (actual time=10383.736..10383.737 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=50394 read=276192
         ->  Hash Anti Join  (cost=596662.73..639609.01 rows=59730 width=20) (actual time=10089.413..10364.486 rows=63287 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=50394 read=276192
               ->  Bitmap Heap Scan on customer  (cost=2943.03..41908.94 rows=140492 width=24) (actual time=702.413..871.172 rows=190468 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,26,19,28,17,10,27}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35166
                     Buffers: shared hit=35184 read=36865
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2907.90 rows=140492 width=0) (actual time=694.878..694.878 rows=190468 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,26,19,28,17,10,27}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=21 read=36862
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=9284.488..9284.488 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=15207 read=239327
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.027..4607.236 rows=15000000 loops=1)
                           Buffers: shared hit=15207 read=239327
 Planning time: 2.231 ms
 Execution time: 10399.035 ms
(34 rows)

COMMIT;
COMMIT