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
				('29', '19', '25', '18', '12', '27', '33')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('29', '19', '25', '18', '12', '27', '33')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693108.16..693108.17 rows=3 width=20) (actual time=19877.283..19877.284 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=302936 read=23672
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52992.18..52992.19 rows=1 width=4) (actual time=1044.760..1044.761 rows=1 loops=1)
           Buffers: shared hit=35283 read=1061
           ->  Bitmap Heap Scan on customer  (cost=6683.41..52032.98 rows=383679 width=4) (actual time=225.589..913.465 rows=382026 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,19,25,18,12,27,33}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35283 read=1061
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6587.49 rows=383679 width=0) (actual time=209.812..209.812 rows=382026 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{29,19,25,18,12,27,33}'::text[]))
                       Buffers: shared hit=8 read=1058
   ->  HashAggregate  (cost=640115.90..640115.94 rows=3 width=20) (actual time=19877.190..19877.193 rows=7 loops=1)
         Buffers: shared hit=302934 read=23672
         ->  Hash Anti Join  (cost=596662.65..639673.98 rows=58922 width=20) (actual time=19017.809..19827.562 rows=63854 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=302934 read=23672
               ->  Bitmap Heap Scan on customer  (cost=2942.95..41911.31 rows=140585 width=24) (actual time=1160.452..1527.068 rows=190544 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,19,25,18,12,27,33}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70469 read=1600
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2907.81 rows=140585 width=0) (actual time=1145.367..1145.367 rows=190544 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,19,25,18,12,27,33}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35292 read=1600
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=17847.903..17847.903 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=232462 read=22072
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.034..7692.436 rows=15015000 loops=1)
                           Buffers: shared hit=232462 read=22072
 Total runtime: 20042.871 ms
(30 rows)

COMMIT;
COMMIT