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', '24', '15', '16', '11', '10', '21')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('30', '24', '15', '16', '11', '10', '21')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694154.87..694154.88 rows=3 width=20) (actual time=12935.506..12935.507 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=168719 read=158125 dirtied=253 written=5
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52933.73..52933.74 rows=1 width=4) (actual time=859.972..859.972 rows=1 loops=1)
           Buffers: shared hit=12 read=36329
           ->  Bitmap Heap Scan on customer customer_1  (cost=6652.96..51976.97 rows=382705 width=4) (actual time=120.941..783.546 rows=381807 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,24,15,16,11,10,21}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=12 read=36329
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6557.28 rows=382705 width=0) (actual time=109.897..109.897 rows=381807 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{30,24,15,16,11,10,21}'::text[]))
                       Buffers: shared hit=9 read=1054
   ->  HashAggregate  (cost=641221.06..641221.10 rows=3 width=20) (actual time=12935.433..12935.435 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=168716 read=158125 dirtied=253 written=5
         ->  Hash Anti Join  (cost=597222.86..640777.98 rows=59077 width=20) (actual time=12137.048..12909.047 rows=63474 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=168716 read=158125 dirtied=253 written=5
               ->  Bitmap Heap Scan on customer  (cost=2913.02..41873.71 rows=140293 width=24) (actual time=937.215..1524.062 rows=190767 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,24,15,16,11,10,21}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35164
                     Buffers: shared hit=5559 read=66492
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2877.94 rows=140293 width=0) (actual time=927.680..927.680 rows=190767 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,24,15,16,11,10,21}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=23 read=36864
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=10733.586..10733.586 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=163154 read=91633 dirtied=253 written=5
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.027..5421.885 rows=15015000 loops=1)
                           Buffers: shared hit=163154 read=91633 dirtied=253 written=5
 Planning time: 4.435 ms
 Execution time: 12952.565 ms
(34 rows)

COMMIT;
COMMIT