diff --git a/bustubx/src/storage/codec/index_page.rs b/bustubx/src/storage/codec/index_page.rs
new file mode 100644
index 0000000..db8ac3e
--- /dev/null
+++ b/bustubx/src/storage/codec/index_page.rs
@@ -0,0 +1,23 @@
+use crate::storage::codec::{CommonCodec, DecodedData};
+use crate::storage::index_page::BPlusTreePageType;
+use crate::{BustubxError, BustubxResult};
+
+pub struct BPlusTreePageTypeCodec;
+
+impl BPlusTreePageTypeCodec {
+    pub fn encode(page_type: &BPlusTreePageType) -> Vec<u8> {
+        match page_type {
+            BPlusTreePageType::LeafPage => CommonCodec::encode_u32(1),
+            BPlusTreePageType::InternalPage => CommonCodec::encode_u32(2),
+        }
+    }
+
+    pub fn decode(bytes: &[u8]) -> BustubxResult<DecodedData<BPlusTreePageType>> {
+        let (flag, offset) = CommonCodec::decode_u32(bytes)?;
+        match flag {
+            1 => Ok((BPlusTreePageType::LeafPage, offset)),
+            2 => Ok((BPlusTreePageType::InternalPage, offset)),
+            _ => Err(BustubxError::Storage("Invalid page type".to_string())),
+        }
+    }
+}
diff --git a/bustubx/src/storage/codec/mod.rs b/bustubx/src/storage/codec/mod.rs
index d1c8538..bc742ca 100644
--- a/bustubx/src/storage/codec/mod.rs
+++ b/bustubx/src/storage/codec/mod.rs
@@ -1,9 +1,11 @@
 mod common;
+mod index_page;
 mod scalar;
 mod table_page;
 mod tuple;
 
 pub use common::CommonCodec;
+pub use index_page::BPlusTreePageTypeCodec;
 pub use scalar::ScalarValueCodec;
 pub use table_page::{TablePageCodec, TablePageHeaderCodec, TablePageHeaderTupleInfoCodec};
 pub use tuple::TupleCodec;
diff --git a/bustubx/src/storage/codec/table_page.rs b/bustubx/src/storage/codec/table_page.rs
index 57a73c7..c9f14c5 100644
--- a/bustubx/src/storage/codec/table_page.rs
+++ b/bustubx/src/storage/codec/table_page.rs
@@ -3,7 +3,7 @@ use crate::catalog::SchemaRef;
 use crate::storage::codec::{CommonCodec, DecodedData};
 use crate::storage::table_page::{TablePageHeader, TupleInfo};
 use crate::storage::{TablePage, TupleMeta};
-use crate::BustubxResult;
+use crate::{BustubxError, BustubxResult};
 
 pub struct TablePageCodec;
 
@@ -16,6 +16,13 @@ impl TablePageCodec {
     }
 
     pub fn decode(bytes: &[u8], schema: SchemaRef) -> BustubxResult<DecodedData<TablePage>> {
+        if bytes.len() != BUSTUBX_PAGE_SIZE {
+            return Err(BustubxError::Storage(format!(
+                "Table page size is not {} instead of {}",
+                BUSTUBX_PAGE_SIZE,
+                bytes.len()
+            )));
+        }
         let (header, offset) = TablePageHeaderCodec::decode(bytes)?;
         let mut data = [0u8; BUSTUBX_PAGE_SIZE];
         data.copy_from_slice(&bytes[0..BUSTUBX_PAGE_SIZE]);
diff --git a/bustubx/src/storage/index_page.rs b/bustubx/src/storage/index_page.rs
index d6fb96a..4d64d72 100644
--- a/bustubx/src/storage/index_page.rs
+++ b/bustubx/src/storage/index_page.rs
@@ -3,6 +3,7 @@ use std::mem::size_of;
 use super::Tuple;
 use crate::buffer::{PageId, BUSTUBX_PAGE_SIZE, INVALID_PAGE_ID};
 use crate::catalog::SchemaRef;
+use crate::storage::codec::BPlusTreePageTypeCodec;
 use crate::{catalog::Schema, common::rid::Rid};
 
 pub const INTERNAL_PAGE_HEADER_SIZE: usize = 4 + 4 + 4;
@@ -25,7 +26,6 @@ impl BPlusTreePage {
             BPlusTreePageType::LeafPage => {
                 Self::Leaf(BPlusTreeLeafPage::from_bytes(raw, key_schema.clone()))
             }
-            BPlusTreePageType::InvalidPage => panic!("Invalid b+ tree page type"),
         };
     }
     pub fn to_bytes(&self) -> [u8; BUSTUBX_PAGE_SIZE] {
@@ -71,14 +71,12 @@ impl BPlusTreePage {
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum BPlusTreePageType {
-    InvalidPage,
     LeafPage,
     InternalPage,
 }
 impl BPlusTreePageType {
     pub fn from_bytes(raw: &[u8; 4]) -> Self {
         match u32::from_be_bytes(*raw) {
-            0 => Self::InvalidPage,
             1 => Self::LeafPage,
             2 => Self::InternalPage,
             _ => panic!("Invalid page type"),
@@ -86,7 +84,6 @@ impl BPlusTreePageType {
     }
     pub fn to_bytes(&self) -> [u8; 4] {
         match self {
-            Self::InvalidPage => 0u32.to_be_bytes(),
             Self::LeafPage => 1u32.to_be_bytes(),
             Self::InternalPage => 2u32.to_be_bytes(),
         }
@@ -322,7 +319,7 @@ impl BPlusTreeInternalPage {
     }
 
     pub fn from_bytes(raw: &[u8; BUSTUBX_PAGE_SIZE], key_schema: SchemaRef) -> Self {
-        let page_type = BPlusTreePageType::from_bytes(&raw[0..4].try_into().unwrap());
+        let (page_type, _) = BPlusTreePageTypeCodec::decode(raw).unwrap();
         let current_size = u32::from_be_bytes(raw[4..8].try_into().unwrap());
         let max_size = u32::from_be_bytes(raw[8..12].try_into().unwrap());
         let mut array = Vec::with_capacity(max_size as usize);
@@ -347,7 +344,7 @@ impl BPlusTreeInternalPage {
 
     pub fn to_bytes(&self) -> [u8; BUSTUBX_PAGE_SIZE] {
         let mut buf = [0; BUSTUBX_PAGE_SIZE];
-        buf[0..4].copy_from_slice(&self.page_type.to_bytes());
+        buf[0..4].copy_from_slice(&BPlusTreePageTypeCodec::encode(&self.page_type));
         buf[4..8].copy_from_slice(&self.current_size.to_be_bytes());
         buf[8..12].copy_from_slice(&self.max_size.to_be_bytes());
         if self.current_size == 0 {
diff --git a/bustubx/src/storage/table_page.rs b/bustubx/src/storage/table_page.rs
index bf7f148..06b68f5 100644
--- a/bustubx/src/storage/table_page.rs
+++ b/bustubx/src/storage/table_page.rs
@@ -39,7 +39,6 @@ pub struct TablePage {
     pub schema: SchemaRef,
     pub header: TablePageHeader,
     // 整个页原始数据
-    // TODO 可以通过memmove、memcpy优化，参考bustub
     pub data: [u8; BUSTUBX_PAGE_SIZE],
 }