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', '10', '31', '21', '24', '26', '30')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '10', '31', '21', '24', '26', '30')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694022.77..694022.78 rows=3 width=20) (actual time=13082.706..13082.706 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=287804 read=39040 written=23
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52857.25..52857.26 rows=1 width=4) (actual time=614.112..614.112 rows=1 loops=1)
           Buffers: shared hit=35285 read=1056
           ->  Bitmap Heap Scan on customer customer_1  (cost=6636.74..51905.72 rows=380609 width=4) (actual time=148.605..524.162 rows=381358 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,10,31,21,24,26,30}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35285 read=1056
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6541.59 rows=380609 width=0) (actual time=135.996..135.996 rows=381358 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,10,31,21,24,26,30}'::text[]))
                       Buffers: shared hit=7 read=1056
   ->  HashAggregate  (cost=641165.44..641165.49 rows=3 width=20) (actual time=13082.644..13082.645 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=287801 read=39040 written=23
         ->  Hash Anti Join  (cost=597214.97..640724.79 rows=58753 width=20) (actual time=12317.618..13058.238 rows=63710 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=287801 read=39040 written=23
               ->  Bitmap Heap Scan on customer  (cost=2905.12..41845.66 rows=139525 width=24) (actual time=681.865..1252.481 rows=190671 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,10,31,21,24,26,30}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35164
                     Buffers: shared hit=35318 read=36733 written=23
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2870.24 rows=139525 width=0) (actual time=672.563..672.563 rows=190671 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,10,31,21,24,26,30}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35294 read=1593
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=11493.130..11493.130 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=252480 read=2307
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.019..4937.711 rows=15015000 loops=1)
                           Buffers: shared hit=252480 read=2307
 Planning time: 3.475 ms
 Execution time: 13108.180 ms
(34 rows)

COMMIT;
COMMIT