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
				('13', '21', '20', '12', '34', '33', '15')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('13', '21', '20', '12', '34', '33', '15')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=697192.79..697192.80 rows=3 width=20) (actual time=10445.146..10445.146 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=259470 read=68644 dirtied=22 written=1708
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52968.09..52968.10 rows=1 width=4) (actual time=551.387..551.387 rows=1 loops=1)
           Buffers: shared hit=35288 read=1056
           ->  Bitmap Heap Scan on customer customer_1  (cost=6679.18..52010.62 rows=382988 width=4) (actual time=102.951..474.070 rows=382779 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,21,20,12,34,33,15}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35288 read=1056
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6583.44 rows=382988 width=0) (actual time=93.663..93.663 rows=382779 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{13,21,20,12,34,33,15}'::text[]))
                       Buffers: shared hit=12 read=1054
   ->  HashAggregate  (cost=644224.62..644224.67 rows=3 width=20) (actual time=10445.088..10445.089 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=259467 read=68644 dirtied=22 written=1708
         ->  Hash Anti Join  (cost=600208.32..643783.00 rows=58883 width=20) (actual time=9762.547..10420.724 rows=63674 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=259467 read=68644 dirtied=22 written=1708
               ->  Bitmap Heap Scan on customer  (cost=2943.10..41909.22 rows=140500 width=24) (actual time=613.273..1153.515 rows=191175 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,21,20,12,34,33,15}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35162
                     Buffers: shared hit=40237 read=31817 written=201
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2907.97 rows=140500 width=0) (actual time=604.642..604.642 rows=191175 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,21,20,12,34,33,15}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35299 read=1593
               ->  Hash  (cost=407703.43..407703.43 rows=15164943 width=4) (actual time=9092.317..9092.317 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=219227 read=36827 dirtied=22 written=1507
                     ->  Seq Scan on orders  (cost=0.00..407703.43 rows=15164943 width=4) (actual time=0.023..4926.227 rows=15000000 loops=1)
                           Buffers: shared hit=219227 read=36827 dirtied=22 written=1507
 Planning time: 2.885 ms
 Execution time: 10449.609 ms
(34 rows)

COMMIT;
COMMIT