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
				('10', '17', '22', '12', '21', '16', '15')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('10', '17', '22', '12', '21', '16', '15')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695285.88..695285.89 rows=3 width=20) (actual time=29640.005..29640.005 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=224960 read=102142 written=4194
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52930.08..52930.09 rows=1 width=4) (actual time=1453.729..1453.729 rows=1 loops=1)
           Buffers: shared hit=35186 read=1158 written=116
           ->  Bitmap Heap Scan on customer  (cost=6651.32..51973.49 rows=382635 width=4) (actual time=225.126..1320.557 rows=382432 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{10,17,22,12,21,16,15}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35186 read=1158 written=116
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6555.67 rows=382635 width=0) (actual time=211.637..211.637 rows=382432 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{10,17,22,12,21,16,15}'::text[]))
                       Buffers: shared hit=10 read=1056 written=103
   ->  HashAggregate  (cost=642355.72..642355.76 rows=3 width=20) (actual time=29639.925..29639.928 rows=7 loops=1)
         Buffers: shared hit=224958 read=102142 written=4194
         ->  Hash Anti Join  (cost=597813.98..641910.65 rows=59342 width=20) (actual time=28146.510..29583.920 rows=63264 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=224958 read=102142 written=4194
               ->  Bitmap Heap Scan on customer  (cost=2911.65..41871.66 rows=140267 width=24) (actual time=1609.981..2518.837 rows=191097 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{10,17,22,12,21,16,15}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70360 read=1696 written=182
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2876.59 rows=140267 width=0) (actual time=1595.795..1595.795 rows=191097 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{10,17,22,12,21,16,15}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35196 read=1696 written=182
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=26528.992..26528.992 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=154595 read=100446 written=4012
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.019..16574.000 rows=15000000 loops=1)
                           Buffers: shared hit=154595 read=100446 written=4012
 Total runtime: 29779.972 ms
(30 rows)

COMMIT;
COMMIT