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
				('27', '30', '31', '10', '28', '26', '20')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('27', '30', '31', '10', '28', '26', '20')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693963.37..693963.37 rows=3 width=20) (actual time=12495.453..12495.453 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=325253 read=1588
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52785.17..52785.18 rows=1 width=4) (actual time=535.602..535.602 rows=1 loops=1)
           Buffers: shared hit=35289 read=1052
           ->  Bitmap Heap Scan on customer  (cost=6604.80..51837.14 rows=379213 width=4) (actual time=93.817..443.366 rows=381150 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,30,31,10,28,26,20}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35289 read=1052
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6509.99 rows=379213 width=0) (actual time=84.828..84.828 rows=381150 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{27,30,31,10,28,26,20}'::text[]))
                       Buffers: shared hit=11 read=1052
   ->  HashAggregate  (cost=641178.12..641178.16 rows=3 width=20) (actual time=12495.377..12495.380 rows=7 loops=1)
         Buffers: shared hit=325251 read=1588
         ->  Hash Anti Join  (cost=597210.37..640736.36 rows=58901 width=20) (actual time=11878.279..12463.555 rows=63769 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=325251 read=1588
               ->  Bitmap Heap Scan on customer  (cost=2900.53..41832.01 rows=139180 width=24) (actual time=637.649..822.855 rows=190815 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,30,31,10,28,26,20}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70461 read=1588
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2865.74 rows=139180 width=0) (actual time=624.913..624.913 rows=190815 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,30,31,10,28,26,20}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35300 read=1588
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=11229.416..11229.416 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=254787
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.032..4826.284 rows=15015000 loops=1)
                           Buffers: shared hit=254787
 Total runtime: 12695.451 ms
(30 rows)

COMMIT;
COMMIT