Begin forwarded message:

From: wrb <wrb@autistici.org>
Subject: Re: [BUGS] BUG #13863: Select from views gives wrong results
Date: 14. ledna 2016 10:49:27 SEČ
To: Haribabu Kommi <kommi.haribabu@gmail.com>

Followup:

This query should show better what's wrong with the optimizer:


select a, count(*)  from test group by cube (a);
a | count
---+-------
1 |     1
2 |     1
 |     2
(3 rows)

select * from (select a, count(*)  from test group by cube (a)) t where a is null;
a | count
---+-------
 |     0

explain select * from (select a, count(*) from test group by cube (a)) t where a is null;
                          QUERY PLAN                            
------------------------------------------------------------------
GroupAggregate  (cost=32.79..32.89 rows=2 width=4)
 Group Key: test.a
 Group Key: ()
 Filter: (test.a IS NULL)
 ->  Sort  (cost=32.79..32.82 rows=11 width=4)
       Sort Key: test.a
       ->  Seq Scan on test  (cost=0.00..32.60 rows=11 width=4)
             Filter: (a IS NULL)


The predicate "a is null" in the outer select should refer to results of inner select and should therefore return (null, 2) instead of no rows, right?

W