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
				('21', '16', '22', '28', '24', '25', '19')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('21', '16', '22', '28', '24', '25', '19')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694725.89..694725.90 rows=3 width=20) (actual time=16233.146..16233.146 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=326349 read=1005
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52903.96..52903.97 rows=1 width=4) (actual time=675.666..675.667 rows=1 loops=1)
           Buffers: shared hit=35742 read=601
           ->  Bitmap Heap Scan on customer  (cost=6645.79..51949.16 rows=381919 width=4) (actual time=144.220..555.718 rows=381828 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,16,22,28,24,25,19}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35742 read=601
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6550.31 rows=381919 width=0) (actual time=131.267..131.267 rows=381828 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{21,16,22,28,24,25,19}'::text[]))
                       Buffers: shared hit=464 read=601
   ->  HashAggregate  (cost=641821.85..641821.89 rows=3 width=20) (actual time=16233.062..16233.064 rows=7 loops=1)
         Buffers: shared hit=326347 read=1005
         ->  Hash Anti Join  (cost=598404.66..641376.33 rows=59403 width=20) (actual time=15504.200..16203.183 rows=63253 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=326347 read=1005
               ->  Bitmap Heap Scan on customer  (cost=2909.86..41865.17 rows=140088 width=24) (actual time=774.101..1065.285 rows=190779 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,16,22,28,24,25,19}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=71049 read=1005
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.84 rows=140088 width=0) (actual time=761.591..761.591 rows=190779 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,16,22,28,24,25,19}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35984 read=906
               ->  Hash  (cost=406494.91..406494.91 rows=15119991 width=4) (actual time=14417.962..14417.962 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=255295
                     ->  Seq Scan on orders  (cost=0.00..406494.91 rows=15119991 width=4) (actual time=0.041..5433.775 rows=15015000 loops=1)
                           Buffers: shared hit=255295
 Total runtime: 16361.281 ms
(30 rows)

COMMIT;
COMMIT