Add column from development database table to production database table

Question

I got an issue When some table on the development database has more columns added, and right now I should add the column in the production database.

I try to add the column manually, by Add Column on Table Tree, but when I try to save, it show me a warning:

here's the complete warning message :

Saving Definition Changes to tables with large amounts of data could take a 
 considerable amount of time. While changes are being saved, 
 table data will not be accessible.

is this safe? or is there another method to do this ?

UPDATE : I Tried to click Yes but after some minutes it give me another warning that said Time Out, and the process canceled, and yes the data in the production table is totally huge

Answer 1

To fix it, go to the Tools Menu and select Options then under Designers select Table and Database Designers the first option allows you to disable the timeout, or make it greater than the default 30 seconds.

Ref: http://surf11.com/entry/197/saving-table-times-out-in-sql-server-200