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
				('23', '15', '16', '25', '13', '19', '33')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('23', '15', '16', '25', '13', '19', '33')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694086.18..694086.18 rows=3 width=20) (actual time=11689.525..11689.526 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=303262 read=23584 dirtied=19 written=749
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52898.47..52898.48 rows=1 width=4) (actual time=531.225..531.225 rows=1 loops=1)
           Buffers: shared hit=35284 read=1060
           ->  Bitmap Heap Scan on customer customer_1  (cost=6645.47..51944.12 rows=381739 width=4) (actual time=105.898..454.265 rows=382805 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{23,15,16,25,13,19,33}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=35284 read=1060
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6550.04 rows=381739 width=0) (actual time=95.993..95.993 rows=382805 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{23,15,16,25,13,19,33}'::text[]))
                       Buffers: shared hit=7 read=1060
   ->  HashAggregate  (cost=641187.63..641187.67 rows=3 width=20) (actual time=11689.424..11689.428 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=303259 read=23584 dirtied=19 written=749
         ->  Hash Anti Join  (cost=597219.63..640741.29 rows=59511 width=20) (actual time=11262.054..11668.406 rows=63411 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=303259 read=23584 dirtied=19 written=749
               ->  Bitmap Heap Scan on customer  (cost=2909.79..41862.18 rows=139977 width=24) (actual time=594.668..826.483 rows=191042 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{23,15,16,25,13,19,33}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35162
                     Buffers: shared hit=70452 read=1601 written=2
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.79 rows=139977 width=0) (actual time=585.636..585.636 rows=191042 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{23,15,16,25,13,19,33}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35295 read=1596
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=10500.256..10500.256 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=232804 read=21983 dirtied=19 written=747
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.033..4639.484 rows=15000000 loops=1)
                           Buffers: shared hit=232804 read=21983 dirtied=19 written=747
 Planning time: 2.699 ms
 Execution time: 11719.896 ms
(34 rows)

COMMIT;
COMMIT