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
				('20', '26', '16', '15', '17', '13', '21')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('20', '26', '16', '15', '17', '13', '21')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=696403.68..696403.69 rows=3 width=20) (actual time=19493.793..19493.795 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=321536 read=6571 written=10
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52850.82..52850.83 rows=1 width=4) (actual time=833.781..833.782 rows=1 loops=1)
           Buffers: shared hit=35596 read=749
           ->  Bitmap Heap Scan on customer  (cost=6634.51..51899.66 rows=380463 width=4) (actual time=155.282..703.810 rows=382795 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,26,16,15,17,13,21}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35596 read=749
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6539.39 rows=380463 width=0) (actual time=142.079..142.079 rows=382795 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{20,26,16,15,17,13,21}'::text[]))
                       Buffers: shared hit=318 read=749
   ->  HashAggregate  (cost=643552.78..643552.83 rows=3 width=20) (actual time=19493.708..19493.711 rows=7 loops=1)
         Buffers: shared hit=321534 read=6571 written=10
         ->  Hash Anti Join  (cost=600168.05..643114.56 rows=58429 width=20) (actual time=18337.613..19449.873 rows=63431 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=321534 read=6571 written=10
               ->  Bitmap Heap Scan on customer  (cost=2902.83..41840.26 rows=139407 width=24) (actual time=945.498..1581.037 rows=191400 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,26,16,15,17,13,21}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=65480 read=6568 written=10
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2867.98 rows=139407 width=0) (actual time=931.285..931.285 rows=191400 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,26,16,15,17,13,21}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35762 read=1132
               ->  Hash  (cost=407703.43..407703.43 rows=15164943 width=4) (actual time=17374.469..17374.469 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=256051 read=3
                     ->  Seq Scan on orders  (cost=0.00..407703.43 rows=15164943 width=4) (actual time=0.031..7133.612 rows=15015000 loops=1)
                           Buffers: shared hit=256051 read=3
 Total runtime: 19614.596 ms
(30 rows)

COMMIT;
COMMIT