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
				('20', '13', '21', '33', '25', '24', '31')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('20', '13', '21', '33', '25', '24', '31')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694073.58..694073.59 rows=3 width=20) (actual time=11819.415..11819.415 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=267375 read=59474 dirtied=253 written=57
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52900.57..52900.58 rows=1 width=4) (actual time=814.638..814.639 rows=1 loops=1)
           Buffers: shared hit=13 read=36327 written=16
           ->  Bitmap Heap Scan on customer customer_1  (cost=6645.91..51946.08 rows=381797 width=4) (actual time=95.421..745.213 rows=381844 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,13,21,33,25,24,31}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=13 read=36327 written=16
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6550.46 rows=381797 width=0) (actual time=86.344..86.344 rows=381844 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{20,13,21,33,25,24,31}'::text[]))
                       Buffers: shared hit=10 read=1053 written=1
   ->  HashAggregate  (cost=641172.93..641172.97 rows=3 width=20) (actual time=11819.355..11819.356 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=267372 read=59474 dirtied=253 written=57
         ->  Hash Anti Join  (cost=597217.41..640727.55 rows=59384 width=20) (actual time=11025.910..11790.005 rows=63687 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=267372 read=59474 dirtied=253 written=57
               ->  Bitmap Heap Scan on customer  (cost=2907.57..41854.40 rows=139765 width=24) (actual time=875.946..1487.073 rows=190748 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,13,21,33,25,24,31}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35168
                     Buffers: shared hit=13078 read=58978 written=56
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.62 rows=139765 width=0) (actual time=867.244..867.244 rows=190748 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,13,21,33,25,24,31}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=24 read=36864 written=16
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=10008.659..10008.659 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=254291 read=496 dirtied=253 written=1
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.021..4328.094 rows=15015000 loops=1)
                           Buffers: shared hit=254291 read=496 dirtied=253 written=1
 Planning time: 3.182 ms
 Execution time: 11835.623 ms
(34 rows)

COMMIT;
COMMIT