Re: BUG #5084: Query gives different number of rows depending on ORDER BY

> Bernt Marius Johnsen wrote:
>> Dump of the database:

To save anyone else the bother, there's a VASTLY simpler testcase for
this one, requiring no tables at all:

test1=# explain select * from (values (1),(null)) v(k) where k = k order by k;
QUERY PLAN
-------------------------------------------------------------------
Sort (cost=0.04..0.04 rows=2 width=4)
Sort Key: "*VALUES*".column1
-> Values Scan on "*VALUES*" (cost=0.00..0.03 rows=2 width=4)
(3 rows)

test1=# explain select * from (values (1),(null)) v(k) where k = k;
QUERY PLAN
-------------------------------------------------------------
Values Scan on "*VALUES*" (cost=0.00..0.03 rows=1 width=4)
Filter: (column1 = column1)
(2 rows)

Notice that the (k = k) qual is being dropped somewhere, which changes
the output since that's a disguised not-null condition.

--
Andrew (irc:RhodiumToad)