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
				('16', '10', '28', '31', '21', '17', '34')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('16', '10', '28', '31', '21', '17', '34')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694699.36..694699.37 rows=3 width=20) (actual time=10572.319..10572.319 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=244644 read=82476 dirtied=1 written=71
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52919.88..52919.89 rows=1 width=4) (actual time=806.184..806.184 rows=1 loops=1)
           Buffers: shared hit=12 read=36330 written=10
           ->  Bitmap Heap Scan on customer customer_1  (cost=6650.03..51964.06 rows=382325 width=4) (actual time=98.526..734.480 rows=382241 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{16,10,28,31,21,17,34}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=12 read=36330 written=10
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6554.45 rows=382325 width=0) (actual time=89.315..89.315 rows=382241 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{16,10,28,31,21,17,34}'::text[]))
                       Buffers: shared hit=8 read=1056
   ->  HashAggregate  (cost=641779.41..641779.45 rows=3 width=20) (actual time=10572.258..10572.261 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=244641 read=82476 dirtied=1 written=71
         ->  Hash Anti Join  (cost=597811.90..641333.41 rows=59466 width=20) (actual time=10175.427..10550.905 rows=63458 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=244641 read=82476 dirtied=1 written=71
               ->  Bitmap Heap Scan on customer  (cost=2909.57..41861.47 rows=139958 width=24) (actual time=871.360..1117.737 rows=191156 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{16,10,28,31,21,17,34}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35185
                     Buffers: shared hit=35154 read=36919 written=10
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.58 rows=139958 width=0) (actual time=862.271..862.271 rows=191156 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{16,10,28,31,21,17,34}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=21 read=36867 written=10
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=9172.220..9172.220 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=209484 read=45557 dirtied=1 written=61
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.017..4268.034 rows=15015000 loops=1)
                           Buffers: shared hit=209484 read=45557 dirtied=1 written=61
 Planning time: 3.015 ms
 Execution time: 10593.983 ms
(34 rows)

COMMIT;
COMMIT