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 bb
WHERE 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)