列重排# group Reordering 目录 重排分区 hash_id partition() hash_partition() round_robin_partition() 重排压缩 duplicate_keep_option drop_nulls() drop_nulls() drop_nans() drop_nans() apply_boolean_mask() unique() distinct() distinct_indices() stable_distinct() unique_count() unique_count() distinct_count() distinct_count()
