In my use case Echo mechanism produces a lot of uncesessary ECHO_LOG data, which I need to discard in routing.
Is it possible to have some callback events where I could check ECHO_LOG-fields and ignore unecessary rows before these are written to database?
There is no high-level event for that, but one thing you could do is simply implement your own Echo listener. If you open unit Echo.Listeners.pas, you will see that implementation of TEchoEventsSubscriber class is very simple. You can simply copy and paste that implementation and add some filters in the events before effectively saving the log. Then use your subscriber instead of TEchoEventsSubscriber class.