Migrating anything will always be hard, sometimes services even migrate IDs (to something that is easier to shard intelligently against). As others mentioned y

Migrating anything will always be hard, sometimes services even migrate IDs (to something that is easier to shard intelligently against). As others mentioned you could either put redirects everywhere, but most services just version their REST APIs and then write glue to tie old interfaces to newer data models, see for example Twitter, Amazon AWS, and Instagram. One other semantic nitpick is that a URL is a subset of URI, which stands for Universal Resource Identifier, so in some sense you could make a philosophical argument that URI and IDs are/should be the same thing. If you were really crazy you could store URLs in your DB (obviously not a good idea for many other reasons).