Fix nullability calculation for CASE statements

apache · Jun 29, 2022 · ffc605d · ffc605d
1 parent 3cfd15b
commit ffc605d
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Showing 2 changed files with 7 additions and 2 deletions.
diff --git a/datafusion/expr/src/expr_schema.rs b/datafusion/expr/src/expr_schema.rs
@@ -170,7 +170,10 @@ impl ExprSchemable for Expr {
                 } else if let Some(e) = else_expr {
                     e.nullable(input_schema)
                 } else {
-                    Ok(false)
+                    println!("AAL IN none else expr");
+                    // CASE produces NULL if there is no `else` expr
+                    // (aka when none of the `when_then_exprs` match)
+                    Ok(true)
                 }
             }
             Expr::Cast { expr, .. } => expr.nullable(input_schema),

diff --git a/datafusion/physical-expr/src/expressions/case.rs b/datafusion/physical-expr/src/expressions/case.rs
@@ -243,7 +243,9 @@ impl PhysicalExpr for CaseExpr {
         } else if let Some(e) = &self.else_expr {
             e.nullable(input_schema)
         } else {
-            Ok(false)
+            // CASE produces NULL if there is no `else` expr
+            // (aka when none of the `when_then_exprs` match)
+            Ok(true)
         }
     }