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
				('23', '34', '15', '21', '32', '28', '12')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('23', '34', '15', '21', '32', '28', '12')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694094.80..694094.81 rows=3 width=20) (actual time=12691.434..12691.435 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=266984 read=59881 written=10
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52891.63..52891.64 rows=1 width=4) (actual time=778.378..778.379 rows=1 loops=1)
           Buffers: shared hit=9 read=36334
           ->  Bitmap Heap Scan on customer customer_1  (cost=6644.01..51937.75 rows=381552 width=4) (actual time=93.403..706.547 rows=382500 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{23,34,15,21,32,28,12}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=9 read=36334
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6548.62 rows=381552 width=0) (actual time=84.436..84.436 rows=382500 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{23,34,15,21,32,28,12}'::text[]))
                       Buffers: shared hit=7 read=1058
   ->  HashAggregate  (cost=641203.09..641203.13 rows=3 width=20) (actual time=12691.381..12691.382 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=266981 read=59881 written=10
         ->  Hash Anti Join  (cost=597219.56..640763.12 rows=58662 width=20) (actual time=12281.137..12670.053 rows=63338 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=266981 read=59881 written=10
               ->  Bitmap Heap Scan on customer  (cost=2909.72..41862.01 rows=139973 width=24) (actual time=838.069..1087.099 rows=191107 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{23,34,15,21,32,28,12}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35181
                     Buffers: shared hit=35199 read=36873
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.72 rows=139973 width=0) (actual time=829.666..829.666 rows=191107 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{23,34,15,21,32,28,12}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=19 read=36872
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=10617.077..10617.077 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=231779 read=23008 written=10
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.039..5113.887 rows=15015000 loops=1)
                           Buffers: shared hit=231779 read=23008 written=10
 Planning time: 2.791 ms
 Execution time: 12707.804 ms
(34 rows)

COMMIT;
COMMIT