#17801 Improve nullability reporting of case expressions

datafusion/core/tests/tpcds_planning.rs

@@ -1052,9 +1052,10 @@ async fn regression_test(query_no: u8, create_physical: bool) -> Result<()> {
     for sql in &sql {
         let df = ctx.sql(sql).await?;
         let (state, plan) = df.into_parts();
-        let plan = state.optimize(&plan)?;
         if create_physical {
             let _ = state.create_physical_plan(&plan).await?;
+        } else {
+            let _ = state.optimize(&plan)?;
         }
     }
 

datafusion/expr/src/expr_fn.rs

@@ -340,6 +340,11 @@ pub fn is_null(expr: Expr) -> Expr {
     Expr::IsNull(Box::new(expr))
 }
 
+/// Create is not null expression
+pub fn is_not_null(expr: Expr) -> Expr {
+    Expr::IsNotNull(Box::new(expr))
+}
+
 /// Create is true expression
 pub fn is_true(expr: Expr) -> Expr {
     Expr::IsTrue(Box::new(expr))