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
				('21', '15', '22', '25', '33', '29', '34')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('21', '15', '22', '25', '33', '29', '34')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=692907.24..692907.24 rows=3 width=20) (actual time=12397.897..12397.898 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=207007 read=119355 dirtied=134 written=5360
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52886.46..52886.47 rows=1 width=4) (actual time=804.235..804.235 rows=1 loops=1)
           Buffers: shared hit=5043 read=31300
           ->  Bitmap Heap Scan on customer customer_1  (cost=6642.92..51932.94 rows=381410 width=4) (actual time=121.059..733.482 rows=382461 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,15,22,25,33,29,34}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=5043 read=31300
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6547.57 rows=381410 width=0) (actual time=109.049..109.049 rows=382461 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{21,15,22,25,33,29,34}'::text[]))
                       Buffers: shared hit=9 read=1056
   ->  HashAggregate  (cost=640020.69..640020.74 rows=3 width=20) (actual time=12397.818..12397.820 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=207004 read=119355 dirtied=134 written=5360
         ->  Hash Anti Join  (cost=596039.20..639580.19 rows=58734 width=20) (actual time=11984.771..12376.785 rows=63702 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=207004 read=119355 dirtied=134 written=5360
               ->  Bitmap Heap Scan on customer  (cost=2909.64..41861.67 rows=139963 width=24) (actual time=886.171..1119.979 rows=191091 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,15,22,25,33,29,34}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35183
                     Buffers: shared hit=39706 read=32369 written=1
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.65 rows=139963 width=0) (actual time=874.199..874.199 rows=191091 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,15,22,25,33,29,34}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=5052 read=31840
               ->  Hash  (cost=404880.36..404880.36 rows=15059936 width=4) (actual time=10925.457..10925.457 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=167295 read=86986 dirtied=134 written=5359
                     ->  Seq Scan on orders  (cost=0.00..404880.36 rows=15059936 width=4) (actual time=0.033..5053.978 rows=15000000 loops=1)
                           Buffers: shared hit=167295 read=86986 dirtied=134 written=5359
 Planning time: 2.614 ms
 Execution time: 12425.221 ms
(34 rows)

COMMIT;
COMMIT