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
				('34', '28', '22', '16', '15', '31', '19')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('34', '28', '22', '16', '15', '31', '19')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693095.77..693095.78 rows=3 width=20) (actual time=10277.513..10277.514 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=141039 read=185564 dirtied=507
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=53013.66..53013.67 rows=1 width=4) (actual time=435.068..435.068 rows=1 loops=1)
           Buffers: shared hit=34082 read=2263
           ->  Bitmap Heap Scan on customer customer_1  (cost=6688.84..52053.06 rows=384237 width=4) (actual time=74.995..364.089 rows=382510 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,28,22,16,15,31,19}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=34082 read=2263
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6592.78 rows=384237 width=0) (actual time=67.894..67.894 rows=382510 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{34,28,22,16,15,31,19}'::text[]))
                       Buffers: shared hit=7 read=1060
   ->  HashAggregate  (cost=640082.04..640082.08 rows=3 width=20) (actual time=10277.454..10277.457 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=141036 read=185564 dirtied=507
         ->  Hash Anti Join  (cost=596666.53..639632.88 rows=59887 width=20) (actual time=10008.675..10259.960 rows=63288 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=141036 read=185564 dirtied=507
               ->  Bitmap Heap Scan on customer  (cost=2946.83..41922.40 rows=140860 width=24) (actual time=486.408..632.072 rows=191244 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,28,22,16,15,31,19}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35171
                     Buffers: shared hit=69263 read=2800
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2911.61 rows=140860 width=0) (actual time=479.056..479.056 rows=191244 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,28,22,16,15,31,19}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=34092 read=2800
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=9392.517..9392.517 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=71770 read=182764 dirtied=507
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.028..4667.466 rows=15000000 loops=1)
                           Buffers: shared hit=71770 read=182764 dirtied=507
 Planning time: 2.406 ms
 Execution time: 10291.035 ms
(34 rows)

COMMIT;
COMMIT