Performance considerations when adding a new column to a big table in Sql Server

Question

I have a table with 100 million rows and 70 columns. I'm planning on adding a new DateTime column to this table but I'm concerned that it might affect its performance. Would it be better to create a new table with the new column and link it to the main table? What are some of the best practices to consider when adding columns to a big table?

P.s.: This is a nullable column. I'll be creating the column with null values intially. My only concern is once data is added to the column, what kind of impact will it have because of the page splits?

Answer 1

Off the top of my head, I don't think it will add any great burden to the system since it will be null values after creation.

That being said a 70 column table with 100 million rows is quite large and adding anything will increase overhead. My main concerns would be on the functional aspect of any insert, update , delete commands to this table with existing stored procs or functions. Adding an extra column needs to be taken account that it does not conflict with hard coded column values. This also takes into account any possible future indexing needs as this could add serious time for transactions to complete and storage space .