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
				('31', '20', '28', '11', '19', '29', '32')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('31', '20', '28', '11', '19', '29', '32')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694950.87..694950.88 rows=3 width=20) (actual time=19061.556..19061.557 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=266703 read=60412
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=53017.90..53017.91 rows=1 width=4) (actual time=859.085..859.085 rows=1 loops=1)
           Buffers: shared hit=35170 read=1173
           ->  Bitmap Heap Scan on customer  (cost=6688.89..52056.94 rows=384383 width=4) (actual time=170.069..715.155 rows=381984 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,20,28,11,19,29,32}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35170 read=1173
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6592.79 rows=384383 width=0) (actual time=157.045..157.045 rows=381984 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{31,20,28,11,19,29,32}'::text[]))
                       Buffers: shared hit=11 read=1054
   ->  HashAggregate  (cost=641932.89..641932.94 rows=3 width=20) (actual time=19061.477..19061.479 rows=7 loops=1)
         Buffers: shared hit=266701 read=60412
         ->  Hash Anti Join  (cost=597849.09..641487.64 rows=59367 width=20) (actual time=17703.282..19005.846 rows=63760 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=266701 read=60412
               ->  Bitmap Heap Scan on customer  (cost=2946.76..41924.88 rows=140957 width=24) (actual time=1017.408..1902.810 rows=190869 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,20,28,11,19,29,32}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35265 read=36804
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2911.52 rows=140957 width=0) (actual time=1003.924..1003.924 rows=190869 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,20,28,11,19,29,32}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35179 read=1712
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=16675.520..16675.520 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=231433 read=23608
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.033..7045.789 rows=15015000 loops=1)
                           Buffers: shared hit=231433 read=23608
 Total runtime: 19175.600 ms
(30 rows)

COMMIT;
COMMIT