Convert table index from Int to Bigint MySQL

Question

I use a little web experience using UID for user authentication.

I recently discovered that UIDs may be larger than I understood among some users, so my int-based system is now inadequate, and I need to convert to bigint.

I cannot lose the results that I already have, but I need to convert the table so that the index containing the uid now has the value bigint. Are there any particular problems changing the type of the index column, and would be as simple as:

ALTER TABLE breadusers MODIFY userid bigint;

?

Answer 1

, , , , - .

, , UID Facebook (..: VARCHAR) . , .: -)

Answer 2

Facebook UID BIGINT (64). Facebook: https://developers.facebook.com/blog/post/45/