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
				('18', '20', '31', '16', '23', '34', '15')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '20', '31', '16', '23', '34', '15')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694114.06..694114.06 rows=3 width=20) (actual time=11659.709..11659.710 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=246764 read=80081 written=105
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52924.02..52924.03 rows=1 width=4) (actual time=860.094..860.094 rows=1 loops=1)
           Buffers: shared hit=22124 read=14221 written=57
           ->  Bitmap Heap Scan on customer customer_1  (cost=6650.90..51967.92 rows=382439 width=4) (actual time=97.175..785.627 rows=382560 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,20,31,16,23,34,15}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=22124 read=14221 written=57
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6555.29 rows=382439 width=0) (actual time=88.323..88.323 rows=382560 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,20,31,16,23,34,15}'::text[]))
                       Buffers: shared hit=8 read=1059 written=1
   ->  HashAggregate  (cost=641189.95..641190.00 rows=3 width=20) (actual time=11659.652..11659.653 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=246761 read=80081 written=105
         ->  Hash Anti Join  (cost=597219.84..640743.82 rows=59484 width=20) (actual time=11275.862..11639.515 rows=63551 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=246761 read=80081 written=105
               ->  Bitmap Heap Scan on customer  (cost=2910.00..41863.00 rows=140000 width=24) (actual time=922.506..1157.863 rows=191313 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,20,31,16,23,34,15}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35158
                     Buffers: shared hit=57292 read=14760 written=58
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.00 rows=140000 width=0) (actual time=913.698..913.698 rows=191313 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,20,31,16,23,34,15}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=22134 read=14760 written=58
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=10231.180..10231.180 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=189466 read=65321 written=47
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.020..4795.034 rows=15015000 loops=1)
                           Buffers: shared hit=189466 read=65321 written=47
 Planning time: 2.914 ms
 Execution time: 11672.169 ms
(34 rows)

COMMIT;
COMMIT