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
				('15', '34', '11', '16', '17', '28', '20')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('15', '34', '11', '16', '17', '28', '20')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694723.63..694723.64 rows=3 width=20) (actual time=9747.720..9747.721 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=230293 read=96819 dirtied=1 written=299
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52911.70..52911.71 rows=1 width=4) (actual time=653.348..653.348 rows=1 loops=1)
           Buffers: shared hit=13136 read=23207 written=285
           ->  Bitmap Heap Scan on customer customer_1  (cost=6648.29..51956.45 rows=382101 width=4) (actual time=95.759..581.534 rows=382460 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,34,11,16,17,28,20}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=13136 read=23207 written=285
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6552.77 rows=382101 width=0) (actual time=86.330..86.330 rows=382460 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{15,34,11,16,17,28,20}'::text[]))
                       Buffers: shared hit=9 read=1056 written=18
   ->  HashAggregate  (cost=641811.85..641811.90 rows=3 width=20) (actual time=9747.670..9747.672 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=230290 read=96819 dirtied=1 written=299
         ->  Hash Anti Join  (cost=597814.56..641370.55 rows=58840 width=20) (actual time=9432.398..9726.957 rows=63466 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=230290 read=96819 dirtied=1 written=299
               ->  Bitmap Heap Scan on customer  (cost=2912.23..41870.92 rows=140217 width=24) (actual time=712.399..898.116 rows=191231 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,34,11,16,17,28,20}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35175
                     Buffers: shared hit=48318 read=23747 written=285
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2877.17 rows=140217 width=0) (actual time=703.941..703.941 rows=191231 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,34,11,16,17,28,20}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=13146 read=23744 written=285
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=8665.509..8665.509 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=181969 read=73072 dirtied=1 written=14
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.018..4419.960 rows=15015000 loops=1)
                           Buffers: shared hit=181969 read=73072 dirtied=1 written=14
 Planning time: 2.734 ms
 Execution time: 9751.902 ms
(34 rows)

COMMIT;
COMMIT