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', '21', '33', '15', '18', '26', '12')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('27', '21', '33', '15', '18', '26', '12')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=690679.77..690679.78 rows=3 width=20) (actual time=9220.180..9220.181 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=324007 read=1598
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52950.19..52950.20 rows=1 width=4) (actual time=429.521..429.522 rows=1 loops=1)
           Buffers: shared hit=35286 read=1059
           ->  Bitmap Heap Scan on customer  (cost=6674.51..51993.87 rows=382528 width=4) (actual time=79.808..356.839 rows=382464 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,21,33,15,18,26,12}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35286 read=1059
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6578.88 rows=382528 width=0) (actual time=72.756..72.756 rows=382464 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{27,21,33,15,18,26,12}'::text[]))
                       Buffers: shared hit=8 read=1059
   ->  HashAggregate  (cost=637729.50..637729.55 rows=3 width=20) (actual time=9220.081..9220.084 rows=7 loops=1)
         Buffers: shared hit=324005 read=1598
         ->  Hash Anti Join  (cost=594299.29..637283.27 rows=59498 width=20) (actual time=8813.802..9200.636 rows=63549 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=324005 read=1598
               ->  Bitmap Heap Scan on customer  (cost=2940.15..41901.34 rows=140312 width=24) (actual time=482.887..623.589 rows=190958 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,21,33,15,18,26,12}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70480 read=1598
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2905.08 rows=140312 width=0) (actual time=475.696..475.696 rows=190958 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,21,33,15,18,26,12}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35295 read=1598
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=8323.072..8323.072 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=253522
                     ->  Seq Scan on orders  (cost=0.00..403671.84 rows=15014984 width=4) (actual time=0.022..4104.330 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Total runtime: 9357.477 ms
(30 rows)

COMMIT;
COMMIT