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
				('16', '22', '31', '30', '18', '10', '25')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('16', '22', '31', '30', '18', '10', '25')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694702.99..694703.00 rows=3 width=20) (actual time=19783.690..19783.690 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=159141 read=167956 written=10
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52880.74..52880.75 rows=1 width=4) (actual time=739.688..739.689 rows=1 loops=1)
           Buffers: shared hit=35233 read=1110
           ->  Bitmap Heap Scan on customer  (cost=6640.85..51927.53 rows=381283 width=4) (actual time=106.834..596.240 rows=381536 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{16,22,31,30,18,10,25}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35233 read=1110
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6545.53 rows=381283 width=0) (actual time=92.435..92.435 rows=381536 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{16,22,31,30,18,10,25}'::text[]))
                       Buffers: shared hit=7 read=1058
   ->  HashAggregate  (cost=641822.17..641822.21 rows=3 width=20) (actual time=19783.624..19783.626 rows=7 loops=1)
         Buffers: shared hit=159139 read=167956 written=10
         ->  Hash Anti Join  (cost=597809.39..641380.51 rows=58888 width=20) (actual time=18269.398..19723.522 rows=63749 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=159139 read=167956 written=10
               ->  Bitmap Heap Scan on customer  (cost=2907.06..41855.34 rows=139820 width=24) (actual time=847.527..1874.485 rows=190821 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{16,22,31,30,18,10,25}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35244 read=36807
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.11 rows=139820 width=0) (actual time=834.200..834.200 rows=190821 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{16,22,31,30,18,10,25}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35242 read=1650
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=17412.486..17412.486 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=123892 read=131149 written=10
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.039..9380.612 rows=15015000 loops=1)
                           Buffers: shared hit=123892 read=131149 written=10
 Total runtime: 19843.015 ms
(30 rows)

COMMIT;
COMMIT