We apply incremental, streamable "joins" (relational queries) for real-time syncing between application client and server. I think much of the initial research in this space was around data pipelines but the killer app (no pun intended) is actually in app development
In Elixir/Erlang there is no global pausing for garbage collection, instead each process is individual garbage collected. And I remember hearing about a strategy that allows you to avoid it entirely by ensuring your process's lifetime is short enough (or heap size big enough) that it basically never happens despite the BEAM (Erlang VM) running with garbage collection.
Edit: my point is that it is likely avoidable through certain coding practices in garbage collected environments.