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', '33', '34', '32', '30', '11', '19')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('20', '33', '34', '32', '30', '11', '19')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=699565.60..699565.60 rows=3 width=20) (actual time=29102.532..29102.532 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=279282 read=49842 dirtied=252
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52962.83..52962.84 rows=1 width=4) (actual time=3391.207..3391.207 rows=1 loops=1)
           Buffers: shared hit=12 read=36332
           ->  Bitmap Heap Scan on customer  (cost=6677.17..52005.64 rows=382875 width=4) (actual time=242.256..3260.827 rows=382205 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,33,34,32,30,11,19}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=12 read=36332
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6581.45 rows=382875 width=0) (actual time=229.210..229.210 rows=382205 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{20,33,34,32,30,11,19}'::text[]))
                       Buffers: shared hit=10 read=1056
   ->  HashAggregate  (cost=646602.69..646602.73 rows=3 width=20) (actual time=29102.460..29102.464 rows=7 loops=1)
         Buffers: shared hit=279280 read=49842 dirtied=252
         ->  Hash Anti Join  (cost=602566.43..646154.93 rows=59701 width=20) (actual time=27126.944..29047.585 rows=64027 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=279280 read=49842 dirtied=252
               ->  Bitmap Heap Scan on customer  (cost=2940.66..41903.19 rows=140363 width=24) (actual time=3539.931..4941.355 rows=190985 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,33,34,32,30,11,19}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35181 read=36872
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2905.57 rows=140363 width=0) (actual time=3524.417..3524.417 rows=190985 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,33,34,32,30,11,19}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=22 read=36870
               ->  Hash  (cost=409314.79..409314.79 rows=15224879 width=4) (actual time=23572.654..23572.654 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=244096 read=12970 dirtied=252
                     ->  Seq Scan on orders  (cost=0.00..409314.79 rows=15224879 width=4) (actual time=0.026..13576.299 rows=15015000 loops=1)
                           Buffers: shared hit=244096 read=12970 dirtied=252
 Total runtime: 29245.656 ms
(30 rows)

COMMIT;
COMMIT