per review

Signed-off-by: discord9 <discord9@163.com>

src/mito2/src/access_layer.rs

@@ -476,9 +476,10 @@ impl TempFileCleaner {
     }
 
     /// Removes the SST and index file from the local atomic dir by the file id.
+    /// This only remove the initial index, Since the index version is always 0 for a new SST, this method should be safe to pass 0.
     pub(crate) async fn clean_by_file_id(&self, file_id: FileId) {
         let sst_key = IndexKey::new(self.region_id, file_id, FileType::Parquet).to_string();
-        let index_key = IndexKey::new(self.region_id, file_id, FileType::Puffin(0)).to_string(); // TODO(discord9): confirm correctness
+        let index_key = IndexKey::new(self.region_id, file_id, FileType::Puffin(0)).to_string();
 
         Self::clean_atomic_dir_files(&self.object_store, &[&sst_key, &index_key]).await;
     }

src/mito2/src/cache/index/result_cache.rs

@@ -35,8 +35,6 @@ const INDEX_RESULT_TYPE: &str = "index_result";
 ///
 /// Row groups can be partially searched. Row groups that not contained in `RowGroupSelection` are not searched.
 /// User can retrieve the partial results and handle uncontained row groups required by the predicate subsequently.
-///
-/// FIXME(discord9): confirm if this key need version?
 pub struct IndexResultCache {
     cache: Cache<(PredicateKey, FileId), Arc<RowGroupSelection>>,
 }

src/mito2/src/engine/puffin_index.rs

@@ -172,8 +172,6 @@ pub(crate) async fn collect_index_entries_from_puffin(
             Some(BlobIndexTypeTargetKey::Inverted) => {
                 let mut inverted_entries = collect_inverted_entries(
                     &reader,
-                    // version is not needed here since rebuild index would be another type of index(and this one will invalidate)
-                    // and building a new index also wouldn't be in the cache
                     region_index_id,
                     inverted_index_cache.as_ref(),
                     &context,