diff --git a/src/common/base/src/bytes.rs b/src/common/base/src/bytes.rs
index 78a872a5cb..96f47588f1 100644
--- a/src/common/base/src/bytes.rs
+++ b/src/common/base/src/bytes.rs
@@ -20,6 +20,16 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 #[derive(Debug, Default, Clone, PartialEq, Eq, PartialOrd, Ord, Deserialize, Serialize)]
 pub struct Bytes(bytes::Bytes);
 
+impl Bytes {
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
 impl From<Bytes> for bytes::Bytes {
     fn from(value: Bytes) -> Self {
         value.0
@@ -92,6 +102,14 @@ impl StringBytes {
     pub fn as_utf8(&self) -> &str {
         unsafe { std::str::from_utf8_unchecked(&self.0) }
     }
+
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
 }
 
 impl From<String> for StringBytes {
@@ -178,6 +196,17 @@ mod tests {
         assert_eq!(world, &bytes);
     }
 
+    #[test]
+    fn test_bytes_len() {
+        let hello = b"hello".to_vec();
+        let bytes = Bytes::from(hello.clone());
+        assert_eq!(bytes.len(), hello.len());
+
+        let zero = b"".to_vec();
+        let bytes = Bytes::from(zero);
+        assert!(bytes.is_empty());
+    }
+
     #[test]
     fn test_string_bytes_from() {
         let hello = "hello".to_string();
@@ -191,6 +220,17 @@ mod tests {
         assert_eq!(&bytes, world);
     }
 
+    #[test]
+    fn test_string_bytes_len() {
+        let hello = "hello".to_string();
+        let bytes = StringBytes::from(hello.clone());
+        assert_eq!(bytes.len(), hello.len());
+
+        let zero = "".to_string();
+        let bytes = StringBytes::from(zero);
+        assert!(bytes.is_empty());
+    }
+
     fn check_str(expect: &str, given: &str) {
         assert_eq!(expect, given);
     }
diff --git a/src/promql/src/engine.rs b/src/promql/src/engine.rs
deleted file mode 100644
index d21a421e22..0000000000
--- a/src/promql/src/engine.rs
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright 2023 Greptime Team
-//
-// 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.
-
-use std::sync::Arc;
-
-use promql_parser::parser::Value;
-
-use crate::error::Result;
-
-mod evaluator;
-mod functions;
-
-pub use evaluator::*;
-
-pub struct Context {}
-
-pub struct Query {}
-
-pub struct Engine {}
-
-impl Engine {
-    pub fn exec(_ctx: &Context, _q: Query) -> Result<Arc<dyn Value>> {
-        unimplemented!();
-    }
-}