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
				('15', '33', '11', '25', '30', '31', '12')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('15', '33', '11', '25', '30', '31', '12')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=690488.32..690488.33 rows=3 width=20) (actual time=8644.658..8644.658 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=323987 read=1595
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52873.86..52873.87 rows=1 width=4) (actual time=457.260..457.261 rows=1 loops=1)
           Buffers: shared hit=35286 read=1056
           ->  Bitmap Heap Scan on customer customer_1  (cost=6640.26..51921.19 rows=381064 width=4) (actual time=83.004..382.166 rows=381928 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,33,11,25,30,31,12}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35286 read=1056
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6545.00 rows=381064 width=0) (actual time=74.707..74.707 rows=381928 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{15,33,11,25,30,31,12}'::text[]))
                       Buffers: shared hit=8 read=1056
   ->  HashAggregate  (cost=637614.38..637614.43 rows=3 width=20) (actual time=8644.573..8644.575 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=323984 read=1595
         ->  Hash Anti Join  (cost=594266.06..637168.94 rows=59392 width=20) (actual time=8398.250..8626.942 rows=63792 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323984 read=1595
               ->  Bitmap Heap Scan on customer  (cost=2906.92..41851.96 rows=139697 width=24) (actual time=508.402..642.878 rows=190844 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,33,11,25,30,31,12}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35164
                     Buffers: shared hit=70459 read=1595
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2871.99 rows=139697 width=0) (actual time=501.166..501.166 rows=190844 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,33,11,25,30,31,12}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35295 read=1595
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=7843.989..7843.989 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=253522
                     ->  Seq Scan on orders  (cost=0.00..403671.84 rows=15014984 width=4) (actual time=0.019..4118.028 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Planning time: 3.880 ms
 Execution time: 8648.585 ms
(34 rows)

COMMIT;
COMMIT