diff --git a/src/mito2/src/memtable/merge_tree/data.rs b/src/mito2/src/memtable/merge_tree/data.rs
index cea4d9baccad..f414ca38f99a 100644
--- a/src/mito2/src/memtable/merge_tree/data.rs
+++ b/src/mito2/src/memtable/merge_tree/data.rs
@@ -678,6 +678,11 @@ impl DataParts {
         }
     }
 
+    pub(crate) fn with_frozen(mut self, frozen: Vec<DataPart>) -> Self {
+        self.frozen = frozen;
+        self
+    }
+
     /// Writes a row into parts.
     pub fn write_row(&mut self, pk_index: PkIndex, kv: KeyValue) {
         self.active.write_row(pk_index, kv)
diff --git a/src/mito2/src/memtable/merge_tree/partition.rs b/src/mito2/src/memtable/merge_tree/partition.rs
index 3bb41b3e0cf9..dc817d134ded 100644
--- a/src/mito2/src/memtable/merge_tree/partition.rs
+++ b/src/mito2/src/memtable/merge_tree/partition.rs
@@ -26,7 +26,7 @@ use store_api::storage::ColumnId;
 
 use crate::error::Result;
 use crate::memtable::key_values::KeyValue;
-use crate::memtable::merge_tree::data::{DataBuffer, DataParts, DATA_INIT_CAP};
+use crate::memtable::merge_tree::data::{DataParts, DATA_INIT_CAP};
 use crate::memtable::merge_tree::metrics::WriteMetrics;
 use crate::memtable::merge_tree::shard::Shard;
 use crate::memtable::merge_tree::shard_builder::ShardBuilder;
@@ -207,10 +207,7 @@ impl Inner {
         };
 
         if inner.metadata.primary_key.is_empty() {
-            let data_parts = DataParts::new(
-                DataBuffer::with_capacity(inner.metadata.clone(), DATA_INIT_CAP),
-                Vec::new(),
-            );
+            let data_parts = DataParts::new(inner.metadata.clone(), DATA_INIT_CAP);
             inner.shards.push(Shard::new(0, None, data_parts));
             inner.active_shard_id = 1;
         }
diff --git a/src/mito2/src/memtable/merge_tree/shard.rs b/src/mito2/src/memtable/merge_tree/shard.rs
index 7299e160d508..86c5ea18f1a2 100644
--- a/src/mito2/src/memtable/merge_tree/shard.rs
+++ b/src/mito2/src/memtable/merge_tree/shard.rs
@@ -17,7 +17,7 @@
 use store_api::metadata::RegionMetadataRef;
 
 use crate::memtable::key_values::KeyValue;
-use crate::memtable::merge_tree::data::{DataBuffer, DataParts, DATA_INIT_CAP};
+use crate::memtable::merge_tree::data::{DataParts, DATA_INIT_CAP};
 use crate::memtable::merge_tree::dict::KeyDictRef;
 use crate::memtable::merge_tree::{PkId, ShardId};
 
@@ -77,10 +77,7 @@ impl Shard {
         Shard {
             shard_id: self.shard_id,
             key_dict: self.key_dict.clone(),
-            data_parts: DataParts::new(
-                DataBuffer::with_capacity(metadata, DATA_INIT_CAP),
-                Vec::new(),
-            ),
+            data_parts: DataParts::new(metadata, DATA_INIT_CAP),
         }
     }
 }
@@ -147,7 +144,7 @@ mod tests {
         }
 
         let dict = dict_builder.finish().unwrap();
-        let data_parts = DataParts::new(DataBuffer::with_capacity(metadata, DATA_INIT_CAP), vec![]);
+        let data_parts = DataParts::new(metadata, DATA_INIT_CAP);
 
         Shard::new(shard_id, Some(Arc::new(dict)), data_parts)
     }
diff --git a/src/mito2/src/memtable/merge_tree/shard_builder.rs b/src/mito2/src/memtable/merge_tree/shard_builder.rs
index 9bf2c27ab5b3..f9a32a17a563 100644
--- a/src/mito2/src/memtable/merge_tree/shard_builder.rs
+++ b/src/mito2/src/memtable/merge_tree/shard_builder.rs
@@ -87,10 +87,7 @@ impl ShardBuilder {
         };
 
         // build data parts.
-        let data_parts = DataParts::new(
-            DataBuffer::with_capacity(metadata, DATA_INIT_CAP),
-            vec![data_part],
-        );
+        let data_parts = DataParts::new(metadata, DATA_INIT_CAP).with_frozen(vec![data_part]);
         let key_dict = key_dict.map(Arc::new);
 
         Ok(Some(Shard::new(shard_id, key_dict, data_parts)))
@@ -168,7 +165,7 @@ mod tests {
         }
 
         let dict = dict_builder.finish().unwrap();
-        let data_parts = DataParts::new(DataBuffer::with_capacity(metadata, DATA_INIT_CAP), vec![]);
+        let data_parts = DataParts::new(metadata, DATA_INIT_CAP);
 
         Shard::new(shard_id, Some(Arc::new(dict)), data_parts)
     }