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
				('17', '33', '18', '13', '26', '25', '31')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('17', '33', '18', '13', '26', '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=696005.28..696005.28 rows=3 width=20) (actual time=10736.521..10736.521 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=223427 read=104182 written=59
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52963.89..52963.90 rows=1 width=4) (actual time=844.689..844.689 rows=1 loops=1)
           Buffers: shared hit=10 read=36333 written=36
           ->  Bitmap Heap Scan on customer customer_1  (cost=6678.26..52006.70 rows=382874 width=4) (actual time=103.503..773.358 rows=382095 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{17,33,18,13,26,25,31}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=10 read=36333 written=36
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6582.54 rows=382874 width=0) (actual time=94.037..94.037 rows=382095 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{17,33,18,13,26,25,31}'::text[]))
                       Buffers: shared hit=8 read=1057 written=2
   ->  HashAggregate  (cost=643041.31..643041.35 rows=3 width=20) (actual time=10736.459..10736.462 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=223424 read=104182 written=59
         ->  Hash Anti Join  (cost=599027.61..642599.82 rows=58865 width=20) (actual time=10301.386..10714.560 rows=63700 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=223424 read=104182 written=59
               ->  Bitmap Heap Scan on customer  (cost=2942.67..41907.69 rows=140458 width=24) (actual time=913.012..1207.675 rows=190857 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{17,33,18,13,26,25,31}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35165
                     Buffers: shared hit=27681 read=44374 written=38
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2907.55 rows=140458 width=0) (actual time=903.754..903.754 rows=190857 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{17,33,18,13,26,25,31}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=20 read=36870 written=36
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=9319.659..9319.659 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=195740 read=59808 written=21
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.021..5023.658 rows=15015000 loops=1)
                           Buffers: shared hit=195740 read=59808 written=21
 Planning time: 3.180 ms
 Execution time: 10742.206 ms
(34 rows)

COMMIT;
COMMIT