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', '11', '15', '10', '12', '14', '31')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('26', '11', '15', '10', '12', '14', '31')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694655.99..694655.99 rows=3 width=20) (actual time=16358.137..16358.139 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=200575 read=126537 dirtied=93 written=5377
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52872.58..52872.59 rows=1 width=4) (actual time=701.581..701.581 rows=1 loops=1)
           Buffers: shared hit=14 read=36327
           ->  Bitmap Heap Scan on customer customer_1  (cost=6639.99..51920.00 rows=381029 width=4) (actual time=80.552..635.410 rows=381525 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,11,15,10,12,14,31}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=14 read=36327
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6544.74 rows=381029 width=0) (actual time=72.827..72.827 rows=381525 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{26,11,15,10,12,14,31}'::text[]))
                       Buffers: shared hit=11 read=1052
   ->  HashAggregate  (cost=641783.33..641783.37 rows=3 width=20) (actual time=16358.073..16358.074 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=200572 read=126537 dirtied=93 written=5377
         ->  Hash Anti Join  (cost=597810.54..641343.27 rows=58675 width=20) (actual time=15682.935..16334.252 rows=63238 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=200572 read=126537 dirtied=93 written=5377
               ->  Bitmap Heap Scan on customer  (cost=2908.21..41856.56 rows=139823 width=24) (actual time=755.566..1229.672 rows=190686 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,11,15,10,12,14,31}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35178
                     Buffers: shared hit=7757 read=64308 written=2851
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2873.25 rows=139823 width=0) (actual time=747.962..747.962 rows=190686 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,11,15,10,12,14,31}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=24 read=36863
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=11635.901..11635.901 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=192812 read=62229 dirtied=93 written=2526
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.251..5178.308 rows=15000000 loops=1)
                           Buffers: shared hit=192812 read=62229 dirtied=93 written=2526
 Planning time: 2.753 ms
 Execution time: 16384.878 ms
(34 rows)

COMMIT;
COMMIT