[CALCITE-1413] New CASE statement simplification

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.9.0
• Fix Version/s: 1.18.0
• Component/s: core
• Assignee: Zoltan Haindrich
• Reporter: Jesus Camacho Rodriguez
• Created: 05/Oct/16 12:50
• Updated: 23/Dec/18 00:12
• Resolved: 17/Oct/18 20:33

Description

Another possible simplification for CASE statements that return boolean values.

CASE
 WHEN p1 THEN e1
 WHEN p2 THEN e2
 ELSE TRUE
END

where e1...en are boolean expressions, can be rewritten into:

(p1 and e1) or (p2 and e2 and not(p1)) or (not(p1) and not(p2))

if p1...pn cannot be nullable.

Issue Links

• causes: CALCITE-2639 FilterReduceExpressionsRule causes ArithmeticException at execution time
• is blocked by: CALCITE-2611 Linq4j code generation failure if one side of an OR contains unknown
• is related to: CALCITE-2631 General improvements in case simplification
• links to: PR#886