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
				('13', '28', '29', '16', '11', '26', '17')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('13', '28', '29', '16', '11', '26', '17')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694136.97..694136.98 rows=3 width=20) (actual time=12995.446..12995.448 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=204191 read=122659
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52937.31..52937.32 rows=1 width=4) (actual time=525.906..525.906 rows=1 loops=1)
           Buffers: shared hit=35288 read=1054
           ->  Bitmap Heap Scan on customer customer_1  (cost=6653.72..51980.30 rows=382803 width=4) (actual time=95.594..444.909 rows=381783 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,28,29,16,11,26,17}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35288 read=1054
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6558.02 rows=382803 width=0) (actual time=86.633..86.633 rows=381783 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{13,28,29,16,11,26,17}'::text[]))
                       Buffers: shared hit=10 read=1054
   ->  HashAggregate  (cost=641199.58..641199.63 rows=3 width=20) (actual time=12995.390..12995.393 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=204188 read=122659
         ->  Hash Anti Join  (cost=597221.21..640753.03 rows=59540 width=20) (actual time=12269.883..12970.157 rows=63402 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=204188 read=122659
               ->  Bitmap Heap Scan on customer  (cost=2911.37..41867.86 rows=140133 width=24) (actual time=589.523..1151.609 rows=190840 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,28,29,16,11,26,17}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35170
                     Buffers: shared hit=35299 read=36758
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2876.33 rows=140133 width=0) (actual time=580.644..580.644 rows=190840 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,28,29,16,11,26,17}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35297 read=1590
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=10013.996..10013.996 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=168886 read=85901
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.196..5104.845 rows=15015000 loops=1)
                           Buffers: shared hit=168886 read=85901
 Planning time: 2.611 ms
 Execution time: 13012.876 ms
(34 rows)

COMMIT;
COMMIT