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
				('18', '30', '24', '19', '31', '22', '23')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '30', '24', '19', '31', '22', '23')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691148.11..691148.12 rows=3 width=20) (actual time=9124.067..9124.068 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=323261 read=2313
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52900.23..52900.24 rows=1 width=4) (actual time=382.188..382.188 rows=1 loops=1)
           Buffers: shared hit=35290 read=1053
           ->  Bitmap Heap Scan on customer customer_1  (cost=6645.85..51945.76 rows=381787 width=4) (actual time=80.533..310.690 rows=381317 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,30,24,19,31,22,23}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35290 read=1053
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6550.41 rows=381787 width=0) (actual time=72.759..72.759 rows=381317 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,30,24,19,31,22,23}'::text[]))
                       Buffers: shared hit=12 read=1053
   ->  HashAggregate  (cost=638247.80..638247.85 rows=3 width=20) (actual time=9123.979..9123.980 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=323258 read=2313
         ->  Hash Anti Join  (cost=594268.93..637805.85 rows=58927 width=20) (actual time=8881.639..9102.433 rows=63589 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323258 read=2313
               ->  Bitmap Heap Scan on customer  (cost=2909.79..41862.18 rows=139977 width=24) (actual time=441.455..549.076 rows=190506 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,30,24,19,31,22,23}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35158
                     Buffers: shared hit=70458 read=1588
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.79 rows=139977 width=0) (actual time=433.306..433.306 rows=190506 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,30,24,19,31,22,23}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35300 read=1588
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=8351.678..8351.678 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=252797 read=725
                     ->  Seq Scan on orders  (cost=0.00..403671.84 rows=15014984 width=4) (actual time=0.014..3516.668 rows=15015000 loops=1)
                           Buffers: shared hit=252797 read=725
 Planning time: 4.443 ms
 Execution time: 9127.846 ms
(34 rows)

COMMIT;
COMMIT