Queries Failing after upgrade to 9.1.6

[Kevin_Traas]

A simple query that's been working since 8.x is now failing since upgrading to 9.1.6 a few days ago (from 9.1.3 installed with precise upgrade).

The query joins two tables via a lookup. The primary key field is sometimes showing up as null in the query results ??

SELECT * FROM a LEFT JOIN b ON b.id1 = a.id1 LEFT JOIN c ON c.id1 = b.id2 WHERE a.field = 'some value';

In the result set, id1 (primary key in a) is set to null zero, one, or more times. This is, obviously, a huge problem, seeing as it's the primary key field that's affected.

I have worked around this issue by modifying the query as follows:

SELECT a.*, c.* FROM a LEFT JOIN b ON b.id1 = a.id1 LEFT JOIN c ON c.id1 = b.id2 WHERE a.field = 'some value';

Excluding fields of b from the result set always returns valid values for id1.

I have no further info at this time, but am willing to dig further and update this report if anyone has any suggestions on what to try.

[RedShift (redshift-gmx)]

Is there any hint in PostgreSQL logs?