How do I reference an Appwrite account in a collection fastest?

For Live Coding Alliance's website I would like to create multiple live coding profiles to switch between for each Appwrite account; clearly I can't make a relation from one database to another. How am I supposed to reference accounts in collections? Do I just create a table in my database called account I reference by the account id and create my relations from there?

I could look up by id but it's a 10-byte/80-bit UID, which causes problems because with inode based databases like SQL/MariaDB it's fastest to search for 64-bit indexes. In my experience with distributed databases we use a 128-bit UID (preferably with a library like linearid that doesn't generate random numbers at runtime) and then pack them up contiguous 64-bit signed integers every x time units. Am I supposed to search through the database for a string? This is very slow with large databases.