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', '11', '13', '26', '15', '21')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('30', '12', '11', '13', '26', '15', '21')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695358.15..695358.16 rows=3 width=20) (actual time=26266.771..26266.772 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=195452 read=131661 written=4016
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52965.55..52965.56 rows=1 width=4) (actual time=2093.795..2093.795 rows=1 loops=1)
           Buffers: shared hit=11 read=36332
           ->  Bitmap Heap Scan on customer  (cost=6677.77..52008.18 rows=382949 width=4) (actual time=279.249..1988.774 rows=381887 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,12,11,13,26,15,21}'::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..6582.03 rows=382949 width=0) (actual time=259.797..259.797 rows=381887 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{30,12,11,13,26,15,21}'::text[]))
                       Buffers: shared hit=9 read=1056
   ->  HashAggregate  (cost=642392.52..642392.57 rows=3 width=20) (actual time=26266.700..26266.702 rows=7 loops=1)
         Buffers: shared hit=195450 read=131661 written=4016
         ->  Hash Anti Join  (cost=597843.20..641947.09 rows=59391 width=20) (actual time=23130.503..26198.718 rows=63511 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=195450 read=131661 written=4016
               ->  Bitmap Heap Scan on customer  (cost=2940.87..41903.90 rows=140382 width=24) (actual time=2221.901..4730.563 rows=190810 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,12,11,13,26,15,21}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=22 read=72045 written=3808
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2905.78 rows=140382 width=0) (actual time=2207.664..2207.664 rows=190810 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,12,11,13,26,15,21}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=20 read=36871
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=20892.352..20892.352 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=195425 read=59616 written=208
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.030..11666.972 rows=15015000 loops=1)
                           Buffers: shared hit=195425 read=59616 written=208
 Total runtime: 26404.900 ms
(30 rows)

COMMIT;
COMMIT