[nvivo]

MySql doesn't have a UUID data type, the UUID() function returns a varchar. The way you store it is mostly preference and driver defaults. The C# driver used to handle binary(16) as Guids, then they deprecated that in favor of CHAR(36). But when dealing with a bilion rows, each byte counts and I'll favor binary(16) because it's smaller and that helps with the index sizes and memory usage.

[th3sly]

but it supports conversion to binary (+shuffle to keep order) using "uuid_to_bin"

[nvivo]

Yes, but this is new to mysql 8, which is pretty recent. Also, I always use uuid v4 to explicitly prevent any ordering.