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
				('30', '12', '33', '34', '29', '13', '15')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('30', '12', '33', '34', '29', '13', '15')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=697018.52..697018.52 rows=3 width=20) (actual time=20368.441..20368.442 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=255422 read=72705 written=116
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52853.38..52853.39 rows=1 width=4) (actual time=1055.572..1055.572 rows=1 loops=1)
           Buffers: shared hit=14585 read=21760
           ->  Bitmap Heap Scan on customer  (cost=6635.05..51902.04 rows=380533 width=4) (actual time=153.563..931.803 rows=382341 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,12,33,34,29,13,15}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=14585 read=21760
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6539.92 rows=380533 width=0) (actual time=133.828..133.828 rows=382341 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{30,12,33,34,29,13,15}'::text[]))
                       Buffers: shared hit=12 read=1055
   ->  HashAggregate  (cost=644165.06..644165.11 rows=3 width=20) (actual time=20368.386..20368.388 rows=7 loops=1)
         Buffers: shared hit=255420 read=72705 written=116
         ->  Hash Anti Join  (cost=600169.48..643724.26 rows=58773 width=20) (actual time=19282.016..20325.631 rows=63934 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=255420 read=72705 written=116
               ->  Bitmap Heap Scan on customer  (cost=2904.26..41845.32 rows=139545 width=24) (actual time=1152.752..1825.029 rows=190974 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,12,33,34,29,13,15}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=14598 read=57470 written=86
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2869.38 rows=139545 width=0) (actual time=1142.901..1142.901 rows=190974 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,12,33,34,29,13,15}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=14596 read=22298
               ->  Hash  (cost=407703.43..407703.43 rows=15164943 width=4) (actual time=18114.329..18114.329 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=240819 read=15235 written=30
                     ->  Seq Scan on orders  (cost=0.00..407703.43 rows=15164943 width=4) (actual time=0.024..7115.088 rows=15015000 loops=1)
                           Buffers: shared hit=240819 read=15235 written=30
 Total runtime: 20480.719 ms
(30 rows)

COMMIT;
COMMIT