Re: could not devise a query plan

Dear Gurus,

Sorry for upping a 13-month-old thread; please tell if I should've opened 
another one.

Here I come again, with another silly join. Please forgive me, but our 
queries are built from blocks :)

VERSION: 7.4.6, 7.4.8, 8.0.0rc4 (sorry, no newer installed right now)

ABSTRACT: The following query fails.
SELECT * FROM  (SELECT a,b FROM cdqp WHERE a=1 AND b=2) AS aa  NATURAL FULL JOIN  (SELECT a,b FROM cdqp WHERE a=1 and
b=2)AS bbWHERE a+b = 3;
 

DETAILS: It seems it's something about the redundant WHERE clauses. If I 
comment (replace with "WHERE true") any of the three WHERE clauses, it works.

Session log: See below.

TIA,

--
G.


serv1:tir=> \d cdqp   Table "pg_temp_20.cdqp" Column |  Type   | Modifiers
--------+---------+----------- a      | integer | b      | integer |

serv1:tir=> SELECT * FROM
serv1:tir->   (SELECT a,b FROM cdqp WHERE a=1 AND b=2) AS aa
serv1:tir->   NATURAL FULL JOIN
serv1:tir->   (SELECT a,b FROM cdqp WHERE a=1 and b=2) AS bb
serv1:tir-> WHERE a+b = 3;
ERROR:  could not devise a query plan for the given query
serv1:tir=> SELECT * FROM
serv1:tir->   (SELECT a,b FROM cdqp WHERE a=1 AND b=2) AS aa
serv1:tir->   NATURAL FULL JOIN
serv1:tir->   (SELECT a,b FROM cdqp WHERE a=1 and b=2) AS bb
serv1:tir-> WHERE true; a | b
---+--- 1 | 2
(1 row)