Protobufs encoding is neither bulky nor slow and Stargate supports multi column and multi row gets and puts with it. There is support for binary encoding also but not multipart – operations with application/octet-stream encoding are limited to single KVs. Multipart/related is not necessarily efficient. Timestamps and column names would be sent as X-headers mixed between the binary blobs, and the part headers and border adds more overhead. The only reason to support it is if someone cannot use protobufs as an alternative to XML. I filed
HBASE-1788 against Stargate for this but set the priority to trivial. Vote to increase.