The schema is not stored, rather think of it this way, a .proto file once it generates an interface for specific language, then this actual code understands the

The schema is not stored, rather think of it this way, a .proto file once it generates an interface for specific language, then this actual code understands the schema. Now on the wire, you simply sent field numbers (e.g. the numbers that you have to manually specify in monotonically increasing way, and never reuse smaller number), and either simple type (int, float) or symbol reference to another. But you never send the actual schema... Now some specific storage formats, might have a duplicate version of that schema, but this may be just part of their design. So the nice thing, is that if you follow some simple rules, like: never reuse previous number, be careful when changing types of existing fields (there are only so and so ways it can go), then you can upgrade independently your services, and the data being pushed. For example if you've added a new field (and new number), then your existing code (that's still compiled with the older schema), might just ignore it, since, even that it's there, there is no endpoint (e.g. method call to read it) for it to be accessed. Off course, it's not so simple. After all, there are tricks, should I simply pass through fields that I do not understand to other services, or should I filter them? I certainly don't know. I wish protos are used more and more, and ways to put them into various databases (like mysql, postgres, sqlite, etc.) is done. Then also formats that store such data in more optimal way, by rearranging such that compression can be gained, and later faster retrieval, etc.