From c7b5eeaf27a6c1f1a707d0f4b9ac6dffe73d9101 Mon Sep 17 00:00:00 2001
From: Christian Salvati <81280761+src255@users.noreply.github.com>
Date: Fri, 21 Oct 2022 02:06:16 -0400
Subject: [PATCH 1/2] Simplify redundant predicates

Write rules to simplify both `a OR a` and `a AND a` to a.
---
 datafusion/optimizer/src/simplify_expressions.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/datafusion/optimizer/src/simplify_expressions.rs b/datafusion/optimizer/src/simplify_expressions.rs
index 03f79feba336..7423d9d75213 100644
--- a/datafusion/optimizer/src/simplify_expressions.rs
+++ b/datafusion/optimizer/src/simplify_expressions.rs
@@ -741,6 +741,12 @@ impl<'a, S: SimplifyInfo> ExprRewriter for Simplifier<'a, S> {
             // Rules for OR
             //
 
+            // A OR A --> A
+            Expr::BinaryExpr(BinaryExpr {
+                left,
+                op: Or,
+                right,
+            }) if &left == &right => *left,
             // true OR A --> true (even if A is null)
             Expr::BinaryExpr(BinaryExpr {
                 left,
@@ -794,6 +800,12 @@ impl<'a, S: SimplifyInfo> ExprRewriter for Simplifier<'a, S> {
             // Rules for AND
             //
 
+            // A AND A --> A
+            Expr::BinaryExpr(BinaryExpr {
+                left,
+                op: And,
+                right,
+            }) if &left == &right => *left,
             // true AND A --> A
             Expr::BinaryExpr(BinaryExpr {
                 left,

From e243e2b841ba9056462b534a05e4ed781404a468 Mon Sep 17 00:00:00 2001
From: Christian Salvati <81280761+src255@users.noreply.github.com>
Date: Sat, 22 Oct 2022 00:12:53 -0400
Subject: [PATCH 2/2] Add test for redudant `or` expression

Test simplification of `a OR a` --> `a` and remove unnecessary rules
introduced in the previous commit.
---
 .../optimizer/src/simplify_expressions.rs     | 32 ++++++++++++-------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/datafusion/optimizer/src/simplify_expressions.rs b/datafusion/optimizer/src/simplify_expressions.rs
index 7423d9d75213..bc3ac6e84b23 100644
--- a/datafusion/optimizer/src/simplify_expressions.rs
+++ b/datafusion/optimizer/src/simplify_expressions.rs
@@ -741,12 +741,6 @@ impl<'a, S: SimplifyInfo> ExprRewriter for Simplifier<'a, S> {
             // Rules for OR
             //
 
-            // A OR A --> A
-            Expr::BinaryExpr(BinaryExpr {
-                left,
-                op: Or,
-                right,
-            }) if &left == &right => *left,
             // true OR A --> true (even if A is null)
             Expr::BinaryExpr(BinaryExpr {
                 left,
@@ -800,12 +794,6 @@ impl<'a, S: SimplifyInfo> ExprRewriter for Simplifier<'a, S> {
             // Rules for AND
             //
 
-            // A AND A --> A
-            Expr::BinaryExpr(BinaryExpr {
-                left,
-                op: And,
-                right,
-            }) if &left == &right => *left,
             // true AND A --> A
             Expr::BinaryExpr(BinaryExpr {
                 left,
@@ -2164,6 +2152,26 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_simplify_optimized_plan_with_or() {
+        let table_scan = test_table_scan();
+        let plan = LogicalPlanBuilder::from(table_scan)
+            .project(vec![col("a")])
+            .unwrap()
+            .filter(or(col("b").gt(lit(1)), col("b").gt(lit(1))))
+            .unwrap()
+            .build()
+            .unwrap();
+
+        assert_optimized_plan_eq(
+            &plan,
+            "\
+            Filter: test.b > Int32(1)\
+            \n  Projection: test.a\
+            \n    TableScan: test",
+        );
+    }
+
     #[test]
     fn test_simplify_optimized_plan_with_composed_and() {
         let table_scan = test_table_scan();