This would probably be the right way to go. I even started working on a solution last year (see other comment), but got side-tracked by real-life issues. My id

This would probably be the right way to go. I even started working on a solution last year (see other comment), but got side-tracked by real-life issues. My idea was to write a PG extension which would handle all the smarts, and expose a set of sql functions which could be called from the application side. Those functions could then be wrapped in nice client libraries to give a consistent mongo-a-like interface across languages, with the client doing the bare-minimum to shuttle data to and from the database server.