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
				('33', '34', '29', '26', '27', '16', '17')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('33', '34', '29', '26', '27', '16', '17')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694615.11..694615.12 rows=3 width=20) (actual time=15460.696..15460.696 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=271510 read=55591 dirtied=42 written=9498
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52831.23..52831.24 rows=1 width=4) (actual time=943.715..943.715 rows=1 loops=1)
           Buffers: shared hit=14 read=36330 written=6062
           ->  Bitmap Heap Scan on customer  (cost=6630.33..51881.41 rows=379927 width=4) (actual time=93.622..847.902 rows=382073 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,34,29,26,27,16,17}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=14 read=36330 written=6062
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6535.35 rows=379927 width=0) (actual time=84.440..84.440 rows=382073 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{33,34,29,26,27,16,17}'::text[]))
                       Buffers: shared hit=12 read=1054 written=49
   ->  HashAggregate  (cost=641783.80..641783.84 rows=3 width=20) (actual time=15460.630..15460.634 rows=7 loops=1)
         Buffers: shared hit=271508 read=55591 dirtied=42 written=9498
         ->  Hash Anti Join  (cost=597805.23..641339.77 rows=59204 width=20) (actual time=14735.948..15411.840 rows=63612 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=271508 read=55591 dirtied=42 written=9498
               ->  Bitmap Heap Scan on customer  (cost=2902.90..41840.46 rows=139412 width=24) (actual time=1054.853..1335.221 rows=191049 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,34,29,26,27,16,17}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35186 read=36869 written=6228
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2868.05 rows=139412 width=0) (actual time=1040.399..1040.399 rows=191049 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,34,29,26,27,16,17}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=23 read=36869 written=6228
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=13669.027..13669.027 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=236319 read=18722 dirtied=42 written=3270
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.018..5574.054 rows=15015000 loops=1)
                           Buffers: shared hit=236319 read=18722 dirtied=42 written=3270
 Total runtime: 15588.298 ms
(30 rows)

COMMIT;
COMMIT