chore(cubestore): Upgrade DF: Avoid needless Arc in DataFrame

Author: srh

rust/cubestore/cubestore/src/store/mod.rs

@@ -61,31 +61,14 @@ pub const ROW_GROUP_SIZE: usize = 16384; // TODO config
 #[derive(Serialize, Deserialize, Hash, Eq, PartialEq, Debug, DeepSizeOf)]
 pub struct DataFrame {
     columns: Vec<Column>,
-    data: Arc<Vec<Row>>,
+    data: Vec<Row>,
 }
 
 impl DataFrame {
     pub fn new(columns: Vec<Column>, data: Vec<Row>) -> DataFrame {
         DataFrame {
             columns,
-            data: Arc::new(data),
-        }
-    }
-
-    pub fn lowercase(&self) -> Self {
-        Self {
-            columns: self
-                .columns
-                .iter()
-                .map(|c| {
-                    Column::new(
-                        c.get_name().to_lowercase(),
-                        c.get_column_type().clone(),
-                        c.get_index().clone(),
-                    )
-                })
-                .collect(),
-            data: self.data.clone(),
+            data,
         }
     }