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', '13', '22', '20', '28', '12', '31')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '13', '22', '20', '28', '12', '31')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=692348.48..692348.49 rows=3 width=20) (actual time=11152.687..11152.688 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=157940 read=168152 written=3
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52905.60..52905.61 rows=1 width=4) (actual time=731.278..731.278 rows=1 loops=1)
           Buffers: shared hit=10995 read=25348
           ->  Bitmap Heap Scan on customer customer_1  (cost=6646.99..51950.76 rows=381934 width=4) (actual time=95.526..659.637 rows=381684 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,13,22,20,28,12,31}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=10995 read=25348
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6551.51 rows=381934 width=0) (actual time=86.988..86.988 rows=381684 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,13,22,20,28,12,31}'::text[]))
                       Buffers: shared hit=8 read=1057
   ->  HashAggregate  (cost=639442.80..639442.85 rows=3 width=20) (actual time=11152.622..11152.625 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=157937 read=168152 written=3
         ->  Hash Anti Join  (cost=595450.57..639002.40 rows=58721 width=20) (actual time=10435.264..11127.803 rows=63591 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=157937 read=168152 written=3
               ->  Bitmap Heap Scan on customer  (cost=2911.15..41867.12 rows=140113 width=24) (actual time=793.120..1345.730 rows=190764 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,13,22,20,28,12,31}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35168
                     Buffers: shared hit=11006 read=61052
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2876.12 rows=140113 width=0) (actual time=784.541..784.541 rows=190764 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,13,22,20,28,12,31}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=11004 read=25886
               ->  Hash  (cost=404477.52..404477.52 rows=15044952 width=4) (actual time=9554.649..9554.649 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=146928 read=107100 written=3
                     ->  Seq Scan on orders  (cost=0.00..404477.52 rows=15044952 width=4) (actual time=0.022..5202.686 rows=15015000 loops=1)
                           Buffers: shared hit=146928 read=107100 written=3
 Planning time: 2.878 ms
 Execution time: 11157.856 ms
(34 rows)

COMMIT;
COMMIT