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)

---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
     joining column's datatypes do not match

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