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
				('29', '16', '12', '33', '31', '22', '30')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('29', '16', '12', '33', '31', '22', '30')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693519.41..693519.42 rows=3 width=20) (actual time=11814.817..11814.818 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=178850 read=147740 written=105
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52912.04..52912.05 rows=1 width=4) (actual time=793.778..793.778 rows=1 loops=1)
           Buffers: shared hit=3526 read=32818
           ->  Bitmap Heap Scan on customer customer_1  (cost=6648.35..51956.76 rows=382111 width=4) (actual time=102.563..723.373 rows=381860 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,16,12,33,31,22,30}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=3526 read=32818
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6552.82 rows=382111 width=0) (actual time=92.552..92.552 rows=381860 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{29,16,12,33,31,22,30}'::text[]))
                       Buffers: shared hit=8 read=1058
   ->  HashAggregate  (cost=640607.29..640607.33 rows=3 width=20) (actual time=11814.741..11814.742 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=178847 read=147740 written=105
         ->  Hash Anti Join  (cost=596630.85..640160.52 rows=59569 width=20) (actual time=11046.795..11789.656 rows=63837 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=178847 read=147740 written=105
               ->  Bitmap Heap Scan on customer  (cost=2911.15..41867.12 rows=140113 width=24) (actual time=858.428..1413.707 rows=191023 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,16,12,33,31,22,30}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35157
                     Buffers: shared hit=3538 read=68512
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2876.12 rows=140113 width=0) (actual time=849.360..849.360 rows=191023 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,16,12,33,31,22,30}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=3536 read=33357
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=10067.065..10067.065 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=175306 read=79228 written=105
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.027..5000.478 rows=15015000 loops=1)
                           Buffers: shared hit=175306 read=79228 written=105
 Planning time: 2.631 ms
 Execution time: 11844.192 ms
(34 rows)

COMMIT;
COMMIT