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
				('26', '34', '16', '23', '22', '31', '12')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('26', '34', '16', '23', '22', '31', '12')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694050.05..694050.06 rows=3 width=20) (actual time=11140.922..11140.923 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=209654 read=117182 dirtied=255 written=86
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52870.54..52870.55 rows=1 width=4) (actual time=474.880..474.880 rows=1 loops=1)
           Buffers: shared hit=35284 read=1059 written=1
           ->  Bitmap Heap Scan on customer customer_1  (cost=6639.56..51918.10 rows=380973 width=4) (actual time=80.238..401.329 rows=381476 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,34,16,23,22,31,12}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35284 read=1059 written=1
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6544.32 rows=380973 width=0) (actual time=72.663..72.663 rows=381476 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{26,34,16,23,22,31,12}'::text[]))
                       Buffers: shared hit=8 read=1057 written=1
   ->  HashAggregate  (cost=641179.43..641179.48 rows=3 width=20) (actual time=11140.865..11140.867 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=209651 read=117182 dirtied=255 written=86
         ->  Hash Anti Join  (cost=597216.47..640739.67 rows=58635 width=20) (actual time=10408.912..11118.296 rows=63139 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=209651 read=117182 dirtied=255 written=86
               ->  Bitmap Heap Scan on customer  (cost=2906.63..41851.02 rows=139672 width=24) (actual time=529.886..1043.293 rows=190998 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,34,16,23,22,31,12}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35152
                     Buffers: shared hit=35296 read=36747 written=42
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2871.71 rows=139672 width=0) (actual time=522.210..522.210 rows=190998 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,34,16,23,22,31,12}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35294 read=1597 written=1
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=9726.626..9726.626 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=174352 read=80435 dirtied=255 written=44
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.022..4426.891 rows=15015000 loops=1)
                           Buffers: shared hit=174352 read=80435 dirtied=255 written=44
 Planning time: 2.216 ms
 Execution time: 11170.818 ms
(34 rows)

COMMIT;
COMMIT