I am working on a registration form for users. Users can sign up to attend some sport events and are automatically assigned a starting number depending on the users type. There are several types of users and all have a specific range of starting numbers. 0001 - 0050: not automatically assigend 0051 - 0600: type 1 0601 - 0650: type 2 1000 - 1300: type 3 ... What would be the best practice, to assign these values to a user and increment the right counter? Storing these values in a database table might be a little tricky. I also could save the configuration in a yaml file, load it from there and write it back. But what about multiple reads and writes at the same time. Can this be handled by a message queue, which ensures that the file (or database table) is sequentially accessed? Thanks for any comment!