From 00080a0828b13fdc15c8d1484e6c88616b48dc6f Mon Sep 17 00:00:00 2001
From: guojn1 <gjn16637211661@163.com>
Date: Wed, 5 Mar 2025 09:44:34 +0800
Subject: [PATCH] [fix][dingo-exec] Support length function

---
 .../calcite/fun/DingoOperatorTable.java       |  8 ++++
 .../io/dingodb/exec/fun/DingoFunFactory.java  |  1 +
 .../java/io/dingodb/exec/fun/LengthFun.java   | 39 +++++++++++++++++++
 3 files changed, 48 insertions(+)
 create mode 100644 dingo-exec/src/main/java/io/dingodb/exec/fun/LengthFun.java

diff --git a/dingo-calcite/src/main/java/io/dingodb/calcite/fun/DingoOperatorTable.java b/dingo-calcite/src/main/java/io/dingodb/calcite/fun/DingoOperatorTable.java
index 9c8652f2b..8cba2b6c0 100644
--- a/dingo-calcite/src/main/java/io/dingodb/calcite/fun/DingoOperatorTable.java
+++ b/dingo-calcite/src/main/java/io/dingodb/calcite/fun/DingoOperatorTable.java
@@ -19,6 +19,7 @@
 import com.google.common.collect.HashMultimap;
 import com.google.common.collect.Multimap;
 import io.dingodb.exec.fun.AutoIncrementFun;
+import io.dingodb.exec.fun.LengthFun;
 import io.dingodb.exec.fun.PowFunFactory;
 import io.dingodb.exec.fun.mysql.InstrFun;
 import io.dingodb.exec.fun.mysql.JsonExtractFun;
@@ -415,6 +416,13 @@ private void init() {
             OperandTypes.STRING,
             SqlFunctionCategory.NUMERIC
         );
+        registerFunction(
+            LengthFun.NAME,
+            ReturnTypes.INTEGER,
+            InferTypes.VARCHAR_1024,
+            OperandTypes.STRING,
+            SqlFunctionCategory.NUMERIC
+        );
     }
 
     public void registerFunction(
diff --git a/dingo-exec/src/main/java/io/dingodb/exec/fun/DingoFunFactory.java b/dingo-exec/src/main/java/io/dingodb/exec/fun/DingoFunFactory.java
index 0516cc412..4a70b094e 100644
--- a/dingo-exec/src/main/java/io/dingodb/exec/fun/DingoFunFactory.java
+++ b/dingo-exec/src/main/java/io/dingodb/exec/fun/DingoFunFactory.java
@@ -69,6 +69,7 @@ private DingoFunFactory() {
         registerBinaryFun(SchemaFun.NAME, SchemaFun.INSTANCE);
         registerUnaryFun(NextValFun.NAME, NextValFun.INSTANCE);
         registerUnaryFun(CurrValFun.NAME, CurrValFun.INSTANCE);
+        registerUnaryFun(LengthFun.NAME, LengthFun.INSTANCE);
     }
 
     public static synchronized DingoFunFactory getInstance() {
diff --git a/dingo-exec/src/main/java/io/dingodb/exec/fun/LengthFun.java b/dingo-exec/src/main/java/io/dingodb/exec/fun/LengthFun.java
new file mode 100644
index 000000000..2ca7a12ab
--- /dev/null
+++ b/dingo-exec/src/main/java/io/dingodb/exec/fun/LengthFun.java
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2021 DataCanvas
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.dingodb.exec.fun;
+
+import io.dingodb.expr.runtime.ExprConfig;
+import io.dingodb.expr.runtime.op.UnaryOp;
+
+import java.io.Serial;
+
+public class LengthFun extends UnaryOp {
+    public static final LengthFun INSTANCE = new LengthFun();
+
+    public static final String NAME = "length";
+    @Serial
+    private static final long serialVersionUID = 1518305554642713272L;
+
+    @Override
+    public Object evalValue(Object value, ExprConfig config) {
+        if (value == null) {
+            return null;
+        } else {
+            return value.toString().length();
+        }
+    }
+}