BUG #2503: Query results differ based on record count of unrelated table.

The following bug has been logged online:

Bug reference:      2503
Logged by:          Russell Francis
Email address:      rfrancis@ev.net
PostgreSQL version: 8.1.4
Operating system:   FreeBSD 6.1
Description:        Query results differ based on record count of unrelated
table.
Details:

Summary:

If a SELECT statement contains a table in it's FROM clause which has 0
records in it, the query will not return any results.  If a record is added
to the table even though it shouldn't modify the results of query, the query
will return the expected result.

The SQL statements below are a trimmed down test case which duplicates this
issue.  The identical SELECT statements return different results depending
on the record count of the unrelated table_b.

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

CREATE TABLE table_a
(
    ta_col_a    INTEGER
);

CREATE TABLE table_b
(
    tb_col_a    INTEGER
);

INSERT INTO table_a ( ta_col_a ) VALUES ( 50 );

SELECT table_a.* FROM table_a, table_b WHERE table_a.ta_col_a > 0;

INSERT INTO table_b ( tb_col_a ) VALUES ( 50 );

SELECT table_a.* FROM table_a, table_b WHERE table_a.ta_col_a > 0;