ulid VS Hashids.java

I really like ULID for this problem (e.g: https://github.com/ahawker/ulid)

- same number of bytes as UUID

- start with a date, so has great locality. Plus you get extra information in the uid that you can extract.

- can be created from an existing date or uuid, and exported to a uuid, so there is a migration path

As the author of a popular ULID implementation in python[1], the spec has no stewardship anymore. The specification repo[2] has plenty of open issues and no real guidance or communication beyond language implementation authors discussing corner cases. The monotonic functionality is ambiguous (at best) and is implemented differently per-languages [3].

Functionality, UUIDv7 might be the _same_ but the hope would be for a more rigid specification for interoperability.

[1]: https://github.com/ahawker/ulid

[2]: https://github.com/ulid/spec

[3]: https://github.com/ulid/spec/issues/11

Looks similar to ULID[0] (I am the author of a popular python implementation[1]).

It appears to have a similar constraint that two ID's generated within the same timestamp (ms, ns) have no strong guarantee of ordering. That might not be a deal breaker depending on your use case but something to consider.

* https://github.com/ulid/spec

* https://github.com/ahawker/ulid

You basically want Hashids but sequential? Why not simple convert a base 10 (0-9) number to hex? (0-F)

I found hashids [1] to be a great compromise between integer ids in the database and copyable non-enumerable strings on the client.

[1] https://hashids.org/

I wonder how this might compare to just storing regular autoincrementing ints in the database, and converting to/from hashids (https://hashids.org/) at the edge. It eliminates the collision concern and stores more compactly at the cost of a tiny amount of encode/decode when processing requests. You’d want to push it down as close to the database layer as possible to avoid inadvertent int ID leaks; I added native hashids support to clickhouse but I’m not sure what other database support might entail.

Since hashids are not really hashes and are not secure at all this is not even achieved. Hashids can be easily decoded without the salt by a simple brute-force attack described by the authors of hashid themselves right on their website: https://hashids.org/

You don't necessarily need to use UUIDs. You could use something like Hashids to generate random strings from your sequential IDs in a reversible way, so that users can't predict what their values will be, but you can decode them as needed.

You should not use UUIDv4 as a primary key. You can use normal int values and then use hashids to make them safe for URL. UUIDv7 might be good to use as well once they are more widely supported as well.