Creating a datasource of type lookup

Good afternoon, in a previous topic I was having issues on creating a lookup through a lookup spec and using said lookup on a native query using an extraction function.

I managed to overcome that problem thankfully but it would be more practical to use SQL queries instead of native ones.

One thing that I’ve read on the documentation is that there’s a datasource type called “lookup”, where you can use the lookup function from Druid SQL.
How can I create a datasource as type lookup? I cant find anything on the documentation specifying this… would really appreciate the help.

My regards,

João Peres