Use primary key or unique index for tag names?

Question

I'm just wondering that, if I implemented a tags system, should I use a primary key on the tag name, or just have the usual primary key with a unique index on the tag name column?

Answer 1

Assuming the tag entity will be used in millions of rows, a numeric column will perform better than a string as a foreign key column. This is why you use surrogate keys

So "just have the usual primary key with a unique index on the tag name column"