andygrove commented on code in PR #11534:
URL: https://github.com/apache/datafusion/pull/11534#discussion_r1683957851
##########
datafusion/physical-expr/src/expressions/case.rs:
##########
@@ -86,13 +108,35 @@ impl CaseExpr {
when_then_expr: Vec<WhenThen>,
else_expr: Option<Arc<dyn PhysicalExpr>>,
) -> Result<Self> {
+ // normalize null literals to None in the else_expr (this already
happens
+ // during SQL planning, but not necessarily for other use cases)
+ let else_expr = match &else_expr {
+ Some(e) => match e.as_any().downcast_ref::<Literal>() {
+ Some(lit) if lit.value().is_null() => None,
+ _ => else_expr,
+ },
+ _ => else_expr,
+ };
+
if when_then_expr.is_empty() {
exec_err!("There must be at least one WHEN clause")
} else {
+ let eval_method = if expr.is_some() {
+ EvalMethod::WithExpression
+ } else if when_then_expr.len() == 1
Review Comment:
I added more comments to explain the rationale and what is safe or not
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