bluestore_compression_min_blob_size vs. bluestore_compression_min_blob_size_<type>

Hi, With Pacific and afterwards, which of the following two settings takes precedence? bluestore_compression_min_blob_size (default 0) bluestore_compression_min_blob_size_<type> (default 8192) I'd assume the more specific setting takes precedence? What's this "blob"? Is it write block? Then, there is no compression for 4K write block? I was not able to find it out from doc, hope someone could help to clarify. Thanks! Tony