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
				('24', '28', '21', '12', '16', '17', '18')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('24', '28', '21', '12', '16', '17', '18')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693630.08..693630.09 rows=3 width=20) (actual time=15298.496..15298.496 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=316341 read=10512
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52950.00..52950.01 rows=1 width=4) (actual time=798.829..798.830 rows=1 loops=1)
           Buffers: shared hit=26368 read=9975
           ->  Bitmap Heap Scan on customer  (cost=6674.46..51993.69 rows=382523 width=4) (actual time=179.300..702.165 rows=382123 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,28,21,12,16,17,18}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=26368 read=9975
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6578.83 rows=382523 width=0) (actual time=161.869..161.869 rows=382123 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{24,28,21,12,16,17,18}'::text[]))
                       Buffers: shared hit=9 read=1057
   ->  HashAggregate  (cost=640680.01..640680.05 rows=3 width=20) (actual time=15298.413..15298.417 rows=7 loops=1)
         Buffers: shared hit=316339 read=10512
         ->  Hash Anti Join  (cost=597249.92..640233.77 rows=59498 width=20) (actual time=14686.147..15272.085 rows=63404 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=316339 read=10512
               ->  Bitmap Heap Scan on customer  (cost=2940.08..41901.22 rows=140310 width=24) (actual time=892.410..1150.246 rows=190834 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,28,21,12,16,17,18}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=61549 read=10512
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2905.01 rows=140310 width=0) (actual time=881.023..881.023 rows=190834 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,28,21,12,16,17,18}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=26378 read=10512
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=13785.128..13785.128 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=0.021..5545.423 rows=15015000 loops=1)
                           Buffers: shared hit=254787
 Total runtime: 15442.463 ms
(30 rows)

COMMIT;
COMMIT