It's different for every site, db backend, etc. If it's just 1 column, and it doesn't store much data, then probably no. If it's a bunch of columns and it's ta

It's different for every site, db backend, etc. If it's just 1 column, and it doesn't store much data, then probably no. If it's a bunch of columns and it's taking up lots of disk, they they probably migrate what they need to a new table and drop the old one. Altering tables is usually not a good idea. In mysql it can stop replication and can mean hours or days of downtime depending on the situation and amount of data.