[sgarland]

> merge databases

You mean combining logically (or even physically) separated databases, collapsing their tuples into one? Why would you do that, and how often does that occur?

> first hand support across various databases/systems

UUIDs? Of the RDBMS most likely to be used (MySQL, Postgres, SQLite) only Postgres has a UUID type. The others store them as strings (please no) or binary types. MariaDB and Oracle have UUID types, and SQL Server has a GUID (essentially the same thing) type, but those are all less commonly seen.

What does have universal support is integers. They scale just fine (PlanetScale uses them [0] internally), and you can use them in a distributed system – if you even need one in the first place – via a variety of methods: interleaved ranges or a central server allocating chunks are two popular methods that come to mind.

[0]: https://github.com/planetscale/discussion/discussions/366

[djbusby]

Sometimes various but similar database get smashed together when companies merge. Or when putting all the things in a "data-lake". Like inventory lot IDs or transaction IDs from 100s of stores local database uploaded to the corporate global DB (eg: Albertsons, Kroger, Walmart)