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
				('11', '28', '30', '26', '32', '24', '17')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('11', '28', '30', '26', '32', '24', '17')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694531.80..694531.81 rows=3 width=20) (actual time=11938.356..11938.358 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=238959 read=88153 written=62
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52793.19..52793.20 rows=1 width=4) (actual time=533.415..533.415 rows=1 loops=1)
           Buffers: shared hit=34937 read=1403
           ->  Bitmap Heap Scan on customer customer_1  (cost=6607.35..51844.68 rows=379403 width=4) (actual time=95.234..456.541 rows=381230 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,28,30,26,32,24,17}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=34937 read=1403
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6512.50 rows=379403 width=0) (actual time=86.532..86.532 rows=381230 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{11,28,30,26,32,24,17}'::text[]))
                       Buffers: shared hit=6 read=1056
   ->  HashAggregate  (cost=641738.53..641738.57 rows=3 width=20) (actual time=11938.284..11938.286 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=238956 read=88153 written=62
         ->  Hash Anti Join  (cost=597804.01..641301.04 rows=58332 width=20) (actual time=11159.261..11914.394 rows=63545 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=238956 read=88153 written=62
               ->  Bitmap Heap Scan on customer  (cost=2901.68..41833.29 rows=139185 width=24) (actual time=593.716..1158.910 rows=190614 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,28,30,26,32,24,17}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35180
                     Buffers: shared hit=34948 read=37117 written=29
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2866.88 rows=139185 width=0) (actual time=585.371..585.371 rows=190614 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,28,30,26,32,24,17}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=34946 read=1939
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=10450.764..10450.764 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=204005 read=51036 written=33
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.021..4764.039 rows=15015000 loops=1)
                           Buffers: shared hit=204005 read=51036 written=33
 Planning time: 2.899 ms
 Execution time: 11944.540 ms
(34 rows)

COMMIT;
COMMIT