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', '18', '25', '10', '26', '31', '33')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('27', '18', '25', '10', '26', '31', '33')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694537.15..694537.16 rows=3 width=20) (actual time=23029.582..23029.584 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=282969 read=44118 written=249
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52784.09..52784.10 rows=1 width=4) (actual time=1725.297..1725.298 rows=1 loops=1)
           Buffers: shared hit=12 read=36330 written=207
           ->  Bitmap Heap Scan on customer  (cost=6604.58..51836.13 rows=379183 width=4) (actual time=281.829..1607.111 rows=381541 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,18,25,10,26,31,33}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=12 read=36330 written=207
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6509.78 rows=379183 width=0) (actual time=264.909..264.909 rows=381541 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{27,18,25,10,26,31,33}'::text[]))
                       Buffers: shared hit=10 read=1054
   ->  HashAggregate  (cost=641752.98..641753.02 rows=3 width=20) (actual time=23029.502..23029.507 rows=7 loops=1)
         Buffers: shared hit=282967 read=44118 written=249
         ->  Hash Anti Join  (cost=597801.14..641309.54 rows=59125 width=20) (actual time=21395.953..22977.619 rows=63673 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=282967 read=44118 written=249
               ->  Bitmap Heap Scan on customer  (cost=2898.81..41825.82 rows=139010 width=24) (actual time=1855.749..2990.065 rows=190646 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,18,25,10,26,31,33}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35086 read=36955 written=246
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2864.06 rows=139010 width=0) (actual time=1837.661..1837.661 rows=190646 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,18,25,10,26,31,33}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=22 read=36867 written=246
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=19531.148..19531.148 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=247878 read=7163 written=3
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.033..12085.120 rows=15015000 loops=1)
                           Buffers: shared hit=247878 read=7163 written=3
 Total runtime: 23131.876 ms
(30 rows)

COMMIT;
COMMIT