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
				('29', '15', '25', '30', '27', '10', '23')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('29', '15', '25', '30', '27', '10', '23')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691882.33..691882.34 rows=3 width=20) (actual time=13306.340..13306.341 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=200525 read=125319
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52971.21..52971.22 rows=1 width=4) (actual time=685.918..685.918 rows=1 loops=1)
           Buffers: shared hit=10566 read=25774
           ->  Bitmap Heap Scan on customer customer_1  (cost=6679.83..52013.53 rows=383074 width=4) (actual time=98.131..612.378 rows=381460 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,15,25,30,27,10,23}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=10566 read=25774
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6584.07 rows=383074 width=0) (actual time=89.341..89.341 rows=381460 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{29,15,25,30,27,10,23}'::text[]))
                       Buffers: shared hit=7 read=1055
   ->  HashAggregate  (cost=638911.04..638911.08 rows=3 width=20) (actual time=13306.284..13306.286 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=200522 read=125319
         ->  Hash Anti Join  (cost=594892.74..638469.32 rows=58896 width=20) (actual time=12557.358..13281.051 rows=63736 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=200522 read=125319
               ->  Bitmap Heap Scan on customer  (cost=2943.46..41910.42 rows=140532 width=24) (actual time=749.129..1293.470 rows=190575 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,15,25,30,27,10,23}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35177
                     Buffers: shared hit=10582 read=61481
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2908.32 rows=140532 width=0) (actual time=740.294..740.294 rows=190575 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,15,25,30,27,10,23}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=10576 read=26310
               ->  Hash  (cost=404074.68..404074.68 rows=15029968 width=4) (actual time=11666.545..11666.545 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=189937 read=63838
                     ->  Seq Scan on orders  (cost=0.00..404074.68 rows=15029968 width=4) (actual time=0.021..5068.562 rows=15015000 loops=1)
                           Buffers: shared hit=189937 read=63838
 Planning time: 2.740 ms
 Execution time: 13314.966 ms
(34 rows)

COMMIT;
COMMIT