UNION ALL query returns incorrect results
Customer reported a UNION ALL query returning incorrect results. The UNION ALL query has 2 legs, but Impala is only returning information from one leg.
Issue can be reproduced in the latest version of Impala. Below is the reproduction case:
The above query produces the following execution plan:
The issue is in operator 4:
It's definitely a bug with predicate placement - that c1 = c2 predicate shouldn't be evaluated outside the right branch of the LEFT JOIN.