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
				('24', '23', '11', '30', '32', '20', '25')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('24', '23', '11', '30', '32', '20', '25')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691016.99..691016.99 rows=3 width=20) (actual time=8497.603..8497.604 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=324000 read=1588
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52809.66..52809.67 rows=1 width=4) (actual time=428.533..428.533 rows=1 loops=1)
           Buffers: shared hit=35287 read=1052
           ->  Bitmap Heap Scan on customer customer_1  (cost=6610.88..51860.02 rows=379853 width=4) (actual time=80.406..353.723 rows=381035 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,23,11,30,32,20,25}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35287 read=1052
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6515.92 rows=379853 width=0) (actual time=72.069..72.069 rows=381035 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{24,23,11,30,32,20,25}'::text[]))
                       Buffers: shared hit=9 read=1052
   ->  HashAggregate  (cost=638207.25..638207.30 rows=3 width=20) (actual time=8497.490..8497.493 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=323997 read=1588
         ->  Hash Anti Join  (cost=594262.47..637769.25 rows=58401 width=20) (actual time=8309.083..8479.558 rows=63704 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323997 read=1588
               ->  Bitmap Heap Scan on customer  (cost=2903.33..41839.27 rows=139350 width=24) (actual time=480.220..561.431 rows=190490 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,23,11,30,32,20,25}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35175
                     Buffers: shared hit=70472 read=1588
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2868.49 rows=139350 width=0) (actual time=472.999..472.999 rows=190490 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,23,11,30,32,20,25}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35297 read=1588
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=7783.068..7783.068 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=253522
                     ->  Seq Scan on orders  (cost=0.00..403671.84 rows=15014984 width=4) (actual time=0.023..4097.954 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Planning time: 4.256 ms
 Execution time: 8501.707 ms
(34 rows)

COMMIT;
COMMIT