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
				('12', '20', '10', '30', '17', '31', '18')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('12', '20', '10', '30', '17', '31', '18')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695757.36..695757.37 rows=3 width=20) (actual time=11645.662..11645.663 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=318741 read=8876 written=586
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52839.26..52839.27 rows=1 width=4) (actual time=502.831..502.832 rows=1 loops=1)
           Buffers: shared hit=35286 read=1056
           ->  Bitmap Heap Scan on customer customer_1  (cost=6617.17..51887.60 rows=380664 width=4) (actual time=93.129..428.955 rows=381758 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,20,10,30,17,31,18}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35286 read=1056
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6522.01 rows=380664 width=0) (actual time=84.152..84.152 rows=381758 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{12,20,10,30,17,31,18}'::text[]))
                       Buffers: shared hit=8 read=1056
   ->  HashAggregate  (cost=642918.02..642918.06 rows=3 width=20) (actual time=11645.600..11645.602 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=318738 read=8876 written=586
         ->  Hash Anti Join  (cost=598988.27..642473.96 rows=59208 width=20) (actual time=11106.258..11621.101 rows=64004 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=318738 read=8876 written=586
               ->  Bitmap Heap Scan on customer  (cost=2903.33..41839.27 rows=139350 width=24) (actual time=563.587..938.129 rows=190867 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,20,10,30,17,31,18}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35174
                     Buffers: shared hit=63209 read=8854 written=583
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2868.49 rows=139350 width=0) (actual time=555.138..555.138 rows=190867 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,20,10,30,17,31,18}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35296 read=1593
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=9767.028..9767.028 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=255526 read=22 written=3
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.022..4555.967 rows=15000000 loops=1)
                           Buffers: shared hit=255526 read=22 written=3
 Planning time: 2.599 ms
 Execution time: 11659.776 ms
(34 rows)

COMMIT;
COMMIT