Re: (PATCH) Adding CORRESPONDING (NULL error)

Erik Rijkers <er@xs4all.nl>

From: "Erik Rijkers" <er@xs4all.nl>
To: "Kerem Kat" <keremkat@gmail.com>
Cc: "Robert Haas" <robertmhaas@gmail.com>, "Tom Lane" <tgl@sss.pgh.pa.us>, pgsql-hackers@postgresql.org
Date: 2011-10-27T12:45:24Z
Lists: pgsql-hackers
(pgsql 9.2devel (25 oct) with your latest CORRESPONDING patch;
linux x86_64 GNU/Linux 2.6.18-274.3.1.el5)

Hi,

here is another peculiarity, which I think is a bug:

-- first without CORRESPONDING:

$ psql -Xaf null.sql
            select 1 a   , 2 b
union all
            select null a, 4 b ;
 a | b
---+---
 1 | 2
   | 4
(2 rows)

-- then with CORRESPONDING:

            select 1 a   , 2 b
union all
corresponding
            select null a, 4 b ;
psql:null.sql:9: ERROR:  failed to find conversion function from unknown to integer


If the null value is in a table column the error does not occur:

drop table if exists t1; create table t1 (a int, b int); insert into t1 values (1,2);
drop table if exists t2; create table t2 (a int, b int); insert into t2 values (null,2);
                select a,b from t1
union all
corresponding
                select a,b from t2 ;
 a | b
---+---
 1 | 2
   | 2
(2 rows)


I'm not sure it is actually a bug; but it seems an unneccessary error.


thanks,

Erik Rijkers