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
				('17', '16', '22', '11', '28', '24', '12')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('17', '16', '22', '11', '28', '24', '12')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=698843.73..698843.73 rows=3 width=20) (actual time=28427.659..28427.659 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=296466 read=32406 dirtied=25 written=1263
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52892.72..52892.73 rows=1 width=4) (actual time=2098.906..2098.907 rows=1 loops=1)
           Buffers: shared hit=30304 read=6037
           ->  Bitmap Heap Scan on customer  (cost=6643.40..51938.69 rows=381611 width=4) (actual time=274.160..1970.149 rows=381261 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{17,16,22,11,28,24,12}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=30304 read=6037
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6548.00 rows=381611 width=0) (actual time=258.581..258.581 rows=381261 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{17,16,22,11,28,24,12}'::text[]))
                       Buffers: shared hit=312 read=752
   ->  HashAggregate  (cost=645950.92..645950.97 rows=3 width=20) (actual time=28427.579..28427.580 rows=7 loops=1)
         Buffers: shared hit=296464 read=32406 dirtied=25 written=1263
         ->  Hash Anti Join  (cost=601943.56..645504.64 rows=59504 width=20) (actual time=25673.719..28358.844 rows=63131 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=296464 read=32406 dirtied=25 written=1263
               ->  Bitmap Heap Scan on customer  (cost=2907.92..41858.30 rows=139900 width=24) (actual time=2276.725..4406.901 rows=190549 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{17,16,22,11,28,24,12}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=48358 read=23696 written=1140
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.95 rows=139900 width=0) (actual time=2254.922..2254.922 rows=190549 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{17,16,22,11,28,24,12}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=30466 read=6421
               ->  Hash  (cost=408911.95..408911.95 rows=15209895 width=4) (actual time=23384.487..23384.487 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=248103 read=8710 dirtied=25 written=123
                     ->  Seq Scan on orders  (cost=0.00..408911.95 rows=15209895 width=4) (actual time=0.037..12906.014 rows=15015000 loops=1)
                           Buffers: shared hit=248103 read=8710 dirtied=25 written=123
 Total runtime: 28602.753 ms
(30 rows)

COMMIT;
COMMIT