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
				('14', '29', '21', '16', '34', '28', '33')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('14', '29', '21', '16', '34', '28', '33')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=696410.48..696410.49 rows=3 width=20) (actual time=20118.742..20118.744 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=312485 read=15127 dirtied=427 written=12
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52897.26..52897.27 rows=1 width=4) (actual time=1510.236..1510.236 rows=1 loops=1)
           Buffers: shared hit=29001 read=7344 written=5
           ->  Bitmap Heap Scan on customer  (cost=6644.38..51942.92 rows=381735 width=4) (actual time=269.945..1381.870 rows=382503 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{14,29,21,16,34,28,33}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=29001 read=7344 written=5
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6548.95 rows=381735 width=0) (actual time=252.587..252.587 rows=382503 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{14,29,21,16,34,28,33}'::text[]))
                       Buffers: shared hit=10 read=1057 written=5
   ->  HashAggregate  (cost=643513.14..643513.19 rows=3 width=20) (actual time=20118.529..20118.533 rows=7 loops=1)
         Buffers: shared hit=312483 read=15127 dirtied=427 written=12
         ->  Hash Anti Join  (cost=598993.22..643069.12 rows=59203 width=20) (actual time=18837.021..20059.291 rows=63658 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=312483 read=15127 dirtied=427 written=12
               ->  Bitmap Heap Scan on customer  (cost=2908.28..41859.63 rows=139937 width=24) (actual time=1663.883..2443.578 rows=191165 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{14,29,21,16,34,28,33}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=58051 read=14008 written=12
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2873.30 rows=139937 width=0) (actual time=1649.097..1649.097 rows=191165 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{14,29,21,16,34,28,33}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=29010 read=7883 written=5
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=17160.640..17160.640 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=254429 read=1119 dirtied=427
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.027..8196.784 rows=15015000 loops=1)
                           Buffers: shared hit=254429 read=1119 dirtied=427
 Total runtime: 20282.949 ms
(30 rows)

COMMIT;
COMMIT