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
				('25', '27', '22', '15', '21', '24', '10')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('25', '27', '22', '15', '21', '24', '10')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694633.87..694633.88 rows=3 width=20) (actual time=11858.173..11858.175 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=181905 read=145204 written=71
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52868.01..52868.02 rows=1 width=4) (actual time=936.799..936.799 rows=1 loops=1)
           Buffers: shared hit=13981 read=22358 written=12
           ->  Bitmap Heap Scan on customer customer_1  (cost=6639.02..51915.75 rows=380904 width=4) (actual time=148.558..827.995 rows=381355 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,27,22,15,21,24,10}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=13981 read=22358 written=12
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6543.79 rows=380904 width=0) (actual time=136.270..136.270 rows=381355 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{25,27,22,15,21,24,10}'::text[]))
                       Buffers: shared hit=9 read=1052 written=3
   ->  HashAggregate  (cost=641765.78..641765.83 rows=3 width=20) (actual time=11858.107..11858.110 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=181902 read=145204 written=71
         ->  Hash Anti Join  (cost=597808.60..641324.79 rows=58799 width=20) (actual time=11093.040..11832.134 rows=63256 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=181902 read=145204 written=71
               ->  Bitmap Heap Scan on customer  (cost=2906.27..41849.64 rows=139633 width=24) (actual time=1004.488..1605.866 rows=190440 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,27,22,15,21,24,10}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35178
                     Buffers: shared hit=13993 read=58069 written=25
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2871.36 rows=139633 width=0) (actual time=995.253..995.253 rows=190440 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,27,22,15,21,24,10}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=13991 read=22893 written=12
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=9990.631..9990.631 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=167906 read=87135 written=46
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.022..5248.395 rows=15015000 loops=1)
                           Buffers: shared hit=167906 read=87135 written=46
 Planning time: 4.222 ms
 Execution time: 11877.529 ms
(34 rows)

COMMIT;
COMMIT