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
				('34', '19', '13', '22', '10', '21', '33')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('34', '19', '13', '22', '10', '21', '33')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694876.58..694876.59 rows=3 width=20) (actual time=15149.615..15149.616 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=118911 read=208188 written=13884
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52972.90..52972.91 rows=1 width=4) (actual time=702.677..702.677 rows=1 loops=1)
           Buffers: shared hit=25 read=36319
           ->  Bitmap Heap Scan on customer  (cost=6679.34..52015.03 rows=383150 width=4) (actual time=88.167..636.039 rows=382222 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,19,13,22,10,21,33}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=25 read=36319
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6583.55 rows=383150 width=0) (actual time=79.372..79.372 rows=382222 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{34,19,13,22,10,21,33}'::text[]))
                       Buffers: shared hit=9 read=1057
   ->  HashAggregate  (cost=641903.60..641903.64 rows=3 width=20) (actual time=15149.550..15149.552 rows=7 loops=1)
         Buffers: shared hit=118909 read=208188 written=13884
         ->  Hash Anti Join  (cost=597845.64..641457.25 rows=59513 width=20) (actual time=14254.956..15120.680 rows=63541 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=118909 read=208188 written=13884
               ->  Bitmap Heap Scan on customer  (cost=2943.31..41912.72 rows=140625 width=24) (actual time=760.564..1317.914 rows=190791 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,19,13,22,10,21,33}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=36 read=72017 written=2368
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2908.16 rows=140625 width=0) (actual time=752.595..752.595 rows=190791 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,19,13,22,10,21,33}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=34 read=36857
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=13486.872..13486.872 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=118870 read=136171 written=11516
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.016..6442.757 rows=15000000 loops=1)
                           Buffers: shared hit=118870 read=136171 written=11516
 Total runtime: 15249.709 ms
(30 rows)

COMMIT;
COMMIT