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
				('19', '33', '17', '25', '23', '27', '31')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('19', '33', '17', '25', '23', '27', '31')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691099.41..691099.42 rows=3 width=20) (actual time=9398.158..9398.159 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=324013 read=1595
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52886.97..52886.98 rows=1 width=4) (actual time=446.636..446.637 rows=1 loops=1)
           Buffers: shared hit=35284 read=1058
           ->  Bitmap Heap Scan on customer customer_1  (cost=6643.03..51933.41 rows=381424 width=4) (actual time=86.499..374.522 rows=381934 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,33,17,25,23,27,31}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35284 read=1058
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6547.68 rows=381424 width=0) (actual time=78.144..78.144 rows=381934 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{19,33,17,25,23,27,31}'::text[]))
                       Buffers: shared hit=6 read=1058
   ->  HashAggregate  (cost=638212.35..638212.40 rows=3 width=20) (actual time=9398.043..9398.045 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=324010 read=1595
         ->  Hash Anti Join  (cost=594265.34..637767.41 rows=59326 width=20) (actual time=9143.329..9380.259 rows=63552 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=324010 read=1595
               ->  Bitmap Heap Scan on customer  (cost=2906.20..41849.44 rows=139628 width=24) (actual time=498.933..628.503 rows=190669 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,33,17,25,23,27,31}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35192
                     Buffers: shared hit=70485 read=1595
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2871.29 rows=139628 width=0) (actual time=491.566..491.566 rows=190669 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,33,17,25,23,27,31}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35293 read=1595
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=8556.162..8556.162 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=253522
                     ->  Seq Scan on orders  (cost=0.00..403671.84 rows=15014984 width=4) (actual time=0.030..4275.205 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Planning time: 3.904 ms
 Execution time: 9402.317 ms
(34 rows)

COMMIT;
COMMIT