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', '10', '31', '24', '26', '18', '32')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('30', '10', '31', '24', '26', '18', '32')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693514.68..693514.69 rows=3 width=20) (actual time=9471.595..9471.596 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=275399 read=51199 dirtied=372 written=3
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52902.25..52902.26 rows=1 width=4) (actual time=471.718..471.718 rows=1 loops=1)
           Buffers: shared hit=35205 read=1136
           ->  Bitmap Heap Scan on customer customer_1  (cost=6646.29..51947.64 rows=381842 width=4) (actual time=77.957..395.556 rows=381299 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,10,31,24,26,18,32}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35205 read=1136
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6550.83 rows=381842 width=0) (actual time=70.211..70.211 rows=381299 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{30,10,31,24,26,18,32}'::text[]))
                       Buffers: shared hit=9 read=1054
   ->  HashAggregate  (cost=640612.36..640612.40 rows=3 width=20) (actual time=9471.533..9471.536 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=275396 read=51199 dirtied=372 written=3
         ->  Hash Anti Join  (cost=596629.63..640171.59 rows=58769 width=20) (actual time=8819.372..9448.685 rows=63732 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=275396 read=51199 dirtied=372 written=3
               ->  Bitmap Heap Scan on customer  (cost=2909.93..41862.67 rows=139990 width=24) (actual time=526.217..997.651 rows=190661 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,10,31,24,26,18,32}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35170
                     Buffers: shared hit=35216 read=36842
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.93 rows=139990 width=0) (actual time=518.374..518.374 rows=190661 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,10,31,24,26,18,32}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35214 read=1674
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=8180.801..8180.801 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=240177 read=14357 dirtied=372 written=3
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.029..3773.107 rows=15015000 loops=1)
                           Buffers: shared hit=240177 read=14357 dirtied=372 written=3
 Planning time: 2.548 ms
 Execution time: 9492.461 ms
(34 rows)

COMMIT;
COMMIT