diff --git a/src/table/block_builder.rs b/src/table/block_builder.rs
index 63166ce7b39b20261d94993ebe19a4ca680305f1..f24a9956152436e27ef210d98c111ad68425426b 100644
--- a/src/table/block_builder.rs
+++ b/src/table/block_builder.rs
@@ -39,7 +39,7 @@ impl BlockBuilder {
         todo!()
     }
 
-    /// 添加数据到block
+    /// 向datablock增加entry
     ///
     /// # Arguments
     ///
@@ -68,7 +68,7 @@ impl BlockBuilder {
         todo!()
     }
 
-    /// 构造block
+    /// 追加Restart points
     ///
     ///
     /// # Examples
@@ -91,7 +91,7 @@ impl BlockBuilder {
         todo!()
     }
 
-    /// 估算当前的block大小
+    /// 估算当前的block大小, 超过一定大小后，写入文件
     ///
     /// # Examples
     ///
diff --git a/src/table/filter_block.rs b/src/table/filter_block.rs
index c24694e120e61ab3a8a99086f45a1b8d68a76ffb..00133829d48b3d8763179b3ac941527325ed275d 100644
--- a/src/table/filter_block.rs
+++ b/src/table/filter_block.rs
@@ -13,6 +13,7 @@ const FILTER_BASE: usize = 1 << FILTER_BASE_LG;
 
 ///
 /// meta block 构建器
+/// FilterBlock，实质上就是SST文件里面的 meta block
 ///
 pub trait FilterBlock {
     fn new_with_policy(policy: FilterPolicyPtr) -> Self;
diff --git a/src/table/format.rs b/src/table/format.rs
index 01c9610c998bfc3f3532bf7df37e4868de6d1577..e082810331dc2420b1e28b128bde167fa603fc8f 100644
--- a/src/table/format.rs
+++ b/src/table/format.rs
@@ -12,26 +12,28 @@ pub const k_max_encoded_length: u32 = 10 + 10;
 /// of two block handles and a magic number.
 pub const k_encoded_length: u32 = 2 * k_max_encoded_length + 8;
 
-// // kTableMagicNumber was picked by running
-// //    echo http://code.google.com/p/leveldb/ | sha1sum
-// // and taking the leading 64 bits.
-// pub const k_table_magic_number: &str = 0xdb4775248b80fb57ull;
+/// Footer 的大小为 48 字节，内容是一个 8 字节的 magic number 和两个 BlockHandle 构成
+/// 在  Footer::EncodeTo 和 Footer::DecodeFrom 中起作用
+/// kTableMagicNumber was picked by running
+///    echo http://code.google.com/p/leveldb/ | sha1sum
+/// and taking the leading 64 bits.
+pub const k_table_magic_number: u64 = 0xdb4775248b80fb57;
 
 /// 1-byte type + 32-bit crc
 pub const k_block_trailer_size: usize = 5;
 
 pub struct BlockHandle {
     // 偏移量
-    offset_: u64,
+    offset: u64,
     //
-    size_: u64
+    size: u64
 }
 
 /// Footer encapsulates the fixed information stored at the tail
 /// end of every table file.
 pub struct Footer {
-    metaindex_handle_: BlockHandle,
-    index_handle_: BlockHandle
+    meta_index_handle: BlockHandle,
+    index_handle: BlockHandle
 }
 
 pub struct BlockContents {
@@ -45,7 +47,7 @@ pub struct BlockContents {
     heap_allocated:bool,
 }
 
-trait BlockTrait {
+trait BlockHandleTrait {
     ///
     /// The offset of the block in the file.
     ///
@@ -102,7 +104,7 @@ trait BlockTrait {
 
 trait FootTrait {
     // The block handle for the metaindex block of the table
-    fn metaindex_handle(&self) -> BlockHandle;
+    fn meta_index_handle(&self) -> BlockHandle;
 
     fn set_metaindex_handle(&mut self, h: BlockHandle);
 
@@ -151,21 +153,21 @@ trait BlockContent {
 
 }
 
-impl BlockTrait for BlockHandle {
+impl BlockHandleTrait for BlockHandle {
     fn offset(&self) -> u64 {
-        self.offset_
+        self.offset
     }
 
     fn set_offset(&mut self, offset: u64) {
-        self.offset_ = offset;
+        self.offset = offset;
     }
 
     fn size(&self) -> u64 {
-        self.size_
+        self.size
     }
 
     fn set_size(&mut self, size: u64) {
-        self.size_ = size;
+        self.size = size;
     }
 
     fn encode_to(&self) -> Result<Slice> {
@@ -190,14 +192,15 @@ impl Default for BlockHandle {
     #[inline]
     fn default() -> Self {
         BlockHandle {
-            offset_: 0,
-            size_: 0,
+            offset: 0,
+            size: 0,
         }
     }
 }
 
 impl FootTrait for Footer {
-    fn metaindex_handle(&self) -> BlockHandle {
+    /// The block handle for the metaindex block of the table
+    fn meta_index_handle(&self) -> BlockHandle {
         todo!()
     }
 
diff --git a/src/table/table_builder.rs b/src/table/table_builder.rs
index 2d7ed0a5e660791d8f05eaee91bc2dbf049a0f04..c2d449260de3aa60f457c410609d47dd5d7f652d 100644
--- a/src/table/table_builder.rs
+++ b/src/table/table_builder.rs
@@ -10,6 +10,12 @@ use crate::util::slice::Slice;
 use crate::util::status::Status;
 use crate::util::unsafe_slice::UnsafeSlice;
 
+/// 在一个 SSTable 中，文件末尾的 Footer 是定长的，
+/// 其他数据都被划分成一个个变长的 block：
+/// index block(@see format.BlockHandle、Footer#index_handle)、
+/// meta_index block(@see format.BlockHandle、Footer#meta_index_handle)、
+/// meta blocks(@see table.FilterBlock)、
+/// data blocks。
 pub struct TableBuilder {
     rep: Box<Rep>
 }
@@ -41,6 +47,7 @@ struct Rep<> {
     pending_index_entry: bool,
     // Handle to add to index block
     // pending_handle 记录需要生成数据索引的数据块在 SSTable 中的偏移量和大小
+    // 也就是说， pending_handle 主要用于表示当前块的offset及size。
     pending_handle: BlockHandle,
 
     compressed_output: Slice,
@@ -57,18 +64,22 @@ impl TableBuilder {
         todo!()
     }
 
+    /// 写入 entry
     pub fn add(&self, key: &UnsafeSlice, value: &UnsafeSlice) {
         todo!()
     }
 
+    /// flush到文件
     pub fn flush(&self) {
         todo!()
     }
 
+    /// block->Finish、压缩
     pub fn write_block(&self, block: &BlockBuilder, handler: &BlockHandle) {
         todo!()
     }
 
+    /// datablock写入文件，添加压缩方式、crc。
     pub fn write_raw_block(&self, block_contents: &UnsafeSlice, compression_type: CompressionType, handler: &BlockHandle) {
         todo!()
     }
@@ -77,6 +88,7 @@ impl TableBuilder {
         todo!()
     }
 
+    /// 剩余datablock写入文件，并生成管理区。
     pub fn finish(&self) -> Status {
         todo!()
     }