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', '30', '21', '14', '19', '23')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('17', '16', '30', '21', '14', '19', '23')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695889.66..695889.67 rows=3 width=20) (actual time=9298.609..9298.611 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=263707 read=63910 dirtied=253
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52907.87..52907.88 rows=1 width=4) (actual time=419.083..419.084 rows=1 loops=1)
           Buffers: shared hit=35286 read=1058
           ->  Bitmap Heap Scan on customer customer_1  (cost=6647.48..51952.88 rows=381996 width=4) (actual time=77.647..348.197 rows=382333 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{17,16,30,21,14,19,23}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35286 read=1058
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6551.98 rows=381996 width=0) (actual time=70.024..70.024 rows=382333 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{17,16,30,21,14,19,23}'::text[]))
                       Buffers: shared hit=8 read=1058
   ->  HashAggregate  (cost=642981.71..642981.76 rows=3 width=20) (actual time=9298.545..9298.547 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=263704 read=63910 dirtied=253
         ->  Hash Anti Join  (cost=598995.44..642540.77 rows=58793 width=20) (actual time=8975.225..9278.618 rows=63547 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=263704 read=63910 dirtied=253
               ->  Bitmap Heap Scan on customer  (cost=2910.51..41864.74 rows=140047 width=24) (actual time=474.228..670.124 rows=190991 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{17,16,30,21,14,19,23}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35173
                     Buffers: shared hit=70468 read=1595
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.49 rows=140047 width=0) (actual time=466.401..466.401 rows=190991 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{17,16,30,21,14,19,23}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35295 read=1595
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=8424.119..8424.119 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=193233 read=62315 dirtied=253
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.036..4115.578 rows=15000000 loops=1)
                           Buffers: shared hit=193233 read=62315 dirtied=253
 Planning time: 2.276 ms
 Execution time: 9302.790 ms
(34 rows)

COMMIT;
COMMIT