fix: Fallback length function with non-string input (#2349)

Co-authored-by: Andy Grove <[email protected]>

Author: wForget

spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala

@@ -1026,6 +1026,9 @@ object QueryPlanSerde extends Logging with CometExprShim {
         }
       case af @ ArrayFilter(_, func) if func.children.head.isInstanceOf[IsNotNull] =>
         convert(af, CometArrayCompact)
+      case l @ Length(child) if child.dataType == BinaryType =>
+        withInfo(l, "Length on BinaryType is not supported")
+        None
       case expr =>
         QueryPlanSerde.exprSerdeMap.get(expr.getClass) match {
           case Some(handler) =>

spark/src/test/scala/org/apache/comet/CometExpressionSuite.scala

@@ -2953,4 +2953,14 @@ class CometExpressionSuite extends CometTestBase with AdaptiveSparkPlanHelper {
     }
   }
 
+  test("test length function") {
+    withTable("t1") {
+      sql(
+        "create table t1 using parquet as select cast(id as string) as c1, cast(id as binary) as c2 from range(10)")
+      // FIXME: Change checkSparkAnswer to checkSparkAnswerAndOperator after resolving
+      //  https://github.com/apache/datafusion-comet/issues/2348
+      checkSparkAnswer("select length(c1), length(c2) AS x FROM t1 ORDER BY c1")
+    }
+  }
+
 }