> GitHub's migration guide tells developers to treat the new IDs as opaque strings and treat them as references. However it was clear that there was some underlying structure to these IDs as we just saw with the bitmasking
Great, so now GitHub can't change the structure of their IDs without breaking this person's code. The lesson is that if you're designing an API and want an ID to be opaque you have to literally encrypt it. I find it really demoralizing as an API designer that I have to treat my API's consumers as adversaries who will knowingly and intentionally ignore guidance in the documentation like this.
> Great, so now GitHub can't change the structure of their IDs without breaking this person's code.
And that is all the fault of the person who treated a documented opaque value as if it has some specific structure.
> The lesson is that if you're designing an API and want an ID to be opaque you have to literally encrypt it.
The lesson is that you should stop caring about breaking people’s code who go against the documentation this way. When it breaks you shrug. Their code was always buggy and it just happened to be working for them until then. You are not their dad. You are not responsible for their misfortune.
> I find it really demoralizing as an API designer that I have to treat my API's consumers as adversaries who will knowingly and intentionally ignore guidance in the documentation like this.
You could also say, if I tell you something is an opaque identifier, and you introspect it, it's your problem if your code breaks. I told you not to do that.
I think more important than worrying about people treating an opaque value as structured data, is wondering _why_ they're doing so. In the case of this blog post, all they wanted to do was construct a URL, which required the in teger database ID. Just make sure you expose what people need, so they don't need to go digging.
Other than that, I agree with what others are saying. If people rely on some undocumented aspect of your IDs, it's on them if that breaks.
You could but you would lose the performance benefits you were seeking by encoding information into the ID. But you could also use a randomized, proprietary base64 alphabet rather than properly encrypting the ID.
XOR encryption is cheap and effective. Make the key the static string "IfYouCanReadThisYourCodeWillBreak" or something akin to that. That way, the key itself will serve as a final warning when (not if) the key gets cracked.
Encoding a type name into an ID is never really something I've viewed as being about performance. Think of it more like an area code, it's an essential part of the identifier that tells you how to interpret the rest of it.
> That repository ID (010:Repository2325298) had a clear structure: 010 is some type enum, followed by a colon, the word Repository, and then the database ID 2325298.
It's a classic length prefix. Repository has 10 chars, Tree has 4.
In database design typically it recommends giving out opaque natural keys, and keeping your monotonically increasing integer IDs secret and used internally.
Maybe. Until your natural key changes. Which happens. A lot.
Exposing a surrogate / generated key that is effectively meaningless seems to be wise. Maybe internally Youtube has an index number for all their videos, but they expose a reasonably meaningless coded value to their consumers.
> Somewhere in GitHub's codebase, there's an if-statement checking when a repository was created to decide which ID format to return.
I doubt it. That's the beauty of GraphQL — each object can store its ID however it wants, and the GraphQL layer encodes it in base64. Then when someone sends a request with a base64-encoded ID, there _might_ be an if-statement (or maybe it just does a lookup on the ID). If anything, the if-statement happens _after_ decoding the ID, not before encoding it.
There was never any if-statement that checked the time — before the migration, IDs were created only in the old format. After the migration, they were created in the new format.
> GitHub's migration guide tells developers to treat the new IDs as opaque strings and treat them as references. However it was clear that there was some underlying structure to these IDs as we just saw with the bitmasking
Great, so now GitHub can't change the structure of their IDs without breaking this person's code. The lesson is that if you're designing an API and want an ID to be opaque you have to literally encrypt it. I find it really demoralizing as an API designer that I have to treat my API's consumers as adversaries who will knowingly and intentionally ignore guidance in the documentation like this.
> Great, so now GitHub can't change the structure of their IDs without breaking this person's code.
And that is all the fault of the person who treated a documented opaque value as if it has some specific structure.
> The lesson is that if you're designing an API and want an ID to be opaque you have to literally encrypt it.
The lesson is that you should stop caring about breaking people’s code who go against the documentation this way. When it breaks you shrug. Their code was always buggy and it just happened to be working for them until then. You are not their dad. You are not responsible for their misfortune.
> I find it really demoralizing as an API designer that I have to treat my API's consumers as adversaries who will knowingly and intentionally ignore guidance in the documentation like this.
You don’t have to.
You could also say, if I tell you something is an opaque identifier, and you introspect it, it's your problem if your code breaks. I told you not to do that.
Once "you" becomes a big enough "them" it becomes a problem again.
I think more important than worrying about people treating an opaque value as structured data, is wondering _why_ they're doing so. In the case of this blog post, all they wanted to do was construct a URL, which required the in teger database ID. Just make sure you expose what people need, so they don't need to go digging.
Other than that, I agree with what others are saying. If people rely on some undocumented aspect of your IDs, it's on them if that breaks.
This is well understood - Hyrum's law.
You don't need encryption, a global_id database column with a randomly generated ID will do.
You could but you would lose the performance benefits you were seeking by encoding information into the ID. But you could also use a randomized, proprietary base64 alphabet rather than properly encrypting the ID.
XOR encryption is cheap and effective. Make the key the static string "IfYouCanReadThisYourCodeWillBreak" or something akin to that. That way, the key itself will serve as a final warning when (not if) the key gets cracked.
Any symmetric encryption is ~free compared to the cost of a network request or db query.
In this particular instance, Speck would be ideal since it supports a 96-bit block size https://en.wikipedia.org/wiki/Speck_(cipher)
A cryptographer may quibble and call that an encoding but I agree.
Encoding a type name into an ID is never really something I've viewed as being about performance. Think of it more like an area code, it's an essential part of the identifier that tells you how to interpret the rest of it.
That's fair, and you could definitely put a prefix and a UUID (or whatever), I failed to consider that.
Hyrum's law is a real sonuvabitch.
The API contract doesn’t stipulate the behavior so GitHub is free to change as they please.
> That repository ID (010:Repository2325298) had a clear structure: 010 is some type enum, followed by a colon, the word Repository, and then the database ID 2325298.
It's a classic length prefix. Repository has 10 chars, Tree has 4.
I just want to point out that Opus 4.5 actually knows this trick and will write the code to decode the IDs if it is working with GitHub's API lol
In database design typically it recommends giving out opaque natural keys, and keeping your monotonically increasing integer IDs secret and used internally.
Maybe. Until your natural key changes. Which happens. A lot.
Exposing a surrogate / generated key that is effectively meaningless seems to be wise. Maybe internally Youtube has an index number for all their videos, but they expose a reasonably meaningless coded value to their consumers.
> Somewhere in GitHub's codebase, there's an if-statement checking when a repository was created to decide which ID format to return.
I doubt it. That's the beauty of GraphQL — each object can store its ID however it wants, and the GraphQL layer encodes it in base64. Then when someone sends a request with a base64-encoded ID, there _might_ be an if-statement (or maybe it just does a lookup on the ID). If anything, the if-statement happens _after_ decoding the ID, not before encoding it.
There was never any if-statement that checked the time — before the migration, IDs were created only in the old format. After the migration, they were created in the new format.