pub fn create_meta_only(
        id: usize,
        file_size: u64,
        first_key: KeyBytes,
        last_key: KeyBytes,
    ) -> Self {
        Self {
            file: FileObject(None, file_size),
            block_meta: vec![],
            block_meta_offset: 0,
            id,
            block_cache: None,
            first_key,
            last_key,
            bloom: None,
            max_ts: 0,
        }
    }
Create a mock SST with only first key + last key metadata
mini-lsm-starter/src/table.rs