[DERBY-6563] NOT elimination for CASE expressions is broken

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 10.10.2.0
• Fix Version/s: 10.10.2.1, 10.11.1.1
• Component/s: SQL
• Issue & fix info: Repro attached
• Bug behavior facts: Wrong query result
• Assignee: Knut Anders Hatlen
• Reporter: Knut Anders Hatlen
• Created: 05/May/14 12:40
• Updated: 09/Sep/16 09:52
• Resolved: 15/Oct/14 16:28

Description

NOT elimination for CASE expressions seems to be broken. Take this example:

ij> select * from sysibm.sysdummy1 where not ( case when ibmreqd = 'Y' then true else true end );
IBM&
----
Y   

1 row selected

Both branches of the CASE expression evaluate to TRUE, so one would expect the predicate "not ( case ... )" to evaluate to FALSE, and the query should return an empty result.

Issue Links

• incorporates: DERBY-6762 Missing method error in CaseExpressionTest
• relates to: DERBY-6759 Derby 10.10 backport issue (fall 2014)