The choice of the routing key in our case was a combination of the unique identifier (UUID) and type of the primary participant of each event in a calendar. This choice was made based on the querying patterns of the consuming application and to maintain a degree of uniqueness.
Sometimes the key to happiness isn’t finding the next upgrade, but appreciating what’s already in front of you. We’re prone to undervaluing what we have and overvaluing what we don’t have yet covet. Sometimes the grass is greener where you water it.