This is where command and query (with subscribe) must be neatly separated. An event A launches an updates of the DB, that launches the query part to react, then

This is where command and query (with subscribe) must be neatly separated. An event A launches an updates of the DB, that launches the query part to react, then stop. There is the risk of having an infinite loop, if the event A is launched by the query part, which is very related to the behavior of your app.