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', '31', '28', '10', '33', '11', '21')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('19', '31', '28', '10', '33', '11', '21')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=696599.72..696599.73 rows=3 width=20) (actual time=15850.052..15850.053 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=254117 read=74017 written=562
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52958.46..52958.47 rows=1 width=4) (actual time=923.994..923.995 rows=1 loops=1)
           Buffers: shared hit=11 read=36332
           ->  Bitmap Heap Scan on customer  (cost=6676.25..52001.57 rows=382755 width=4) (actual time=138.422..828.923 rows=382142 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,31,28,10,33,11,21}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=11 read=36332
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6580.56 rows=382755 width=0) (actual time=126.185..126.185 rows=382142 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{19,31,28,10,33,11,21}'::text[]))
                       Buffers: shared hit=8 read=1057
   ->  HashAggregate  (cost=643641.18..643641.23 rows=3 width=20) (actual time=15849.982..15849.985 rows=7 loops=1)
         Buffers: shared hit=254115 read=74017 written=562
         ->  Hash Anti Join  (cost=600206.16..643194.68 rows=59534 width=20) (actual time=14582.465..15797.984 rows=63589 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=254115 read=74017 written=562
               ->  Bitmap Heap Scan on customer  (cost=2940.94..41904.31 rows=140395 width=24) (actual time=989.706..1713.829 rows=190811 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,31,28,10,33,11,21}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=24 read=72051 written=522
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2905.85 rows=140395 width=0) (actual time=980.600..980.600 rows=190811 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,31,28,10,33,11,21}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=21 read=36868
               ->  Hash  (cost=407703.43..407703.43 rows=15164943 width=4) (actual time=13581.009..13581.009 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=254088 read=1966 written=40
                     ->  Seq Scan on orders  (cost=0.00..407703.43 rows=15164943 width=4) (actual time=0.017..5693.941 rows=15000000 loops=1)
                           Buffers: shared hit=254088 read=1966 written=40
 Total runtime: 15983.219 ms
(30 rows)

COMMIT;
COMMIT