From e82707ec5a912dc5f23e9fe89bea5f49ec64688f Mon Sep 17 00:00:00 2001
From: Ashim Sedhain <38435962+asimsedhain@users.noreply.github.com>
Date: Mon, 1 Jan 2024 11:44:27 -0600
Subject: [PATCH] feat: simplify null in list (#8691)

GH-8688
---
 .../simplify_expressions/expr_simplifier.rs   | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs b/datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs
index 5a300e2ff246..7d09aec7e748 100644
--- a/datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs
+++ b/datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs
@@ -481,6 +481,14 @@ impl<'a, S: SimplifyInfo> TreeNodeRewriter for Simplifier<'a, S> {
                 lit(negated)
             }
 
+            // null in (x, y, z) --> null
+            // null not in (x, y, z) --> null
+            Expr::InList(InList {
+                expr,
+                list: _,
+                negated: _,
+            }) if is_null(&expr) => lit_bool_null(),
+
             // expr IN ((subquery)) -> expr IN (subquery), see ##5529
             Expr::InList(InList {
                 expr,
@@ -3096,6 +3104,18 @@ mod tests {
         assert_eq!(simplify(in_list(col("c1"), vec![], false)), lit(false));
         assert_eq!(simplify(in_list(col("c1"), vec![], true)), lit(true));
 
+        // null in (...)  --> null
+        assert_eq!(
+            simplify(in_list(lit_bool_null(), vec![col("c1"), lit(1)], false)),
+            lit_bool_null()
+        );
+
+        // null not in (...)  --> null
+        assert_eq!(
+            simplify(in_list(lit_bool_null(), vec![col("c1"), lit(1)], true)),
+            lit_bool_null()
+        );
+
         assert_eq!(
             simplify(in_list(col("c1"), vec![lit(1)], false)),
             col("c1").eq(lit(1))