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
				('31', '15', '24', '21', '23', '30', '14')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('31', '15', '24', '21', '23', '30', '14')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694248.07..694248.07 rows=3 width=20) (actual time=10770.146..10770.146 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=204505 read=122336 written=1061
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52995.55..52995.56 rows=1 width=4) (actual time=518.177..518.177 rows=1 loops=1)
           Buffers: shared hit=35269 read=1073 written=62
           ->  Bitmap Heap Scan on customer customer_1  (cost=6684.99..52036.19 rows=383741 width=4) (actual time=87.754..441.675 rows=381736 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,15,24,21,23,30,14}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35269 read=1073 written=62
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6589.05 rows=383741 width=0) (actual time=79.517..79.517 rows=381736 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{31,15,24,21,23,30,14}'::text[]))
                       Buffers: shared hit=10 read=1054 written=60
   ->  HashAggregate  (cost=641252.44..641252.49 rows=3 width=20) (actual time=10770.088..10770.089 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=204502 read=122336 written=1061
         ->  Hash Anti Join  (cost=597252.72..640804.79 rows=59687 width=20) (actual time=10071.347..10744.693 rows=63464 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=204502 read=122336 written=1061
               ->  Bitmap Heap Scan on customer  (cost=2942.88..41908.40 rows=140477 width=24) (actual time=575.705..1114.550 rows=190750 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,15,24,21,23,30,14}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35160
                     Buffers: shared hit=35280 read=36768 written=89
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2907.76 rows=140477 width=0) (actual time=567.807..567.807 rows=190750 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,15,24,21,23,30,14}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35278 read=1610 written=89
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=9288.718..9288.718 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=169219 read=85568 written=972
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.022..4641.580 rows=15000000 loops=1)
                           Buffers: shared hit=169219 read=85568 written=972
 Planning time: 2.612 ms
 Execution time: 10790.086 ms
(34 rows)

COMMIT;
COMMIT