A document with a key containing a dot can be created via update. The Ruby driver has check_keys = false for update so that operator modifier doc args can specify subdocs, ex., "x.y". However this allows dots to leak in via actual document update. The server does not check this at present. We should investigate this and put in a check to prohibit dots in keys for actual document update, hopefully in an clean and efficient manner. Also consider whether to expose check_keys via the API for efficiency, with appropriate warnings in documentation, etc.

Reference CS-3514 and SERVER-1988