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
				('21', '30', '34', '14', '11', '31', '28')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('21', '30', '34', '14', '11', '31', '28')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694042.69..694042.70 rows=3 width=20) (actual time=11532.363..11532.365 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=234635 read=92240 written=1975
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52861.45..52861.46 rows=1 width=4) (actual time=557.325..557.325 rows=1 loops=1)
           Buffers: shared hit=35282 read=1059 written=50
           ->  Bitmap Heap Scan on customer customer_1  (cost=6637.61..51909.64 rows=380725 width=4) (actual time=99.266..477.571 rows=381535 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,30,34,14,11,31,28}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35282 read=1059 written=50
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6542.43 rows=380725 width=0) (actual time=89.999..89.999 rows=381535 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{21,30,34,14,11,31,28}'::text[]))
                       Buffers: shared hit=7 read=1056 written=50
   ->  HashAggregate  (cost=641181.16..641181.20 rows=3 width=20) (actual time=11532.308..11532.310 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=234632 read=92240 written=1975
         ->  Hash Anti Join  (cost=597216.47..640742.14 rows=58535 width=20) (actual time=11168.320..11512.235 rows=63664 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=234632 read=92240 written=1975
               ->  Bitmap Heap Scan on customer  (cost=2906.63..41850.97 rows=139670 width=24) (actual time=621.546..844.694 rows=190749 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,30,34,14,11,31,28}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35195
                     Buffers: shared hit=70485 read=1597 written=85
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2871.71 rows=139670 width=0) (actual time=612.736..612.736 rows=190749 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,30,34,14,11,31,28}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35291 read=1596 written=85
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=10438.610..10438.610 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=164144 read=90643 written=1890
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.021..5100.697 rows=15000000 loops=1)
                           Buffers: shared hit=164144 read=90643 written=1890
 Planning time: 2.784 ms
 Execution time: 11537.331 ms
(34 rows)

COMMIT;
COMMIT