I have a table with over 70 million rows in and I have viewed the execution plan which has identified a missing index. I took a snapshot of data a short while ago and created this index on a local test database (which was fast to create) and the improvement is exactly what is needed in the live system. What I'd like to know is, is there anyway to tell how long it will take to create on the live system?
Actually - it depends on many things like
If index is relatively wide - it can take from minutes to hours.
if you have your DB on Enterprise Edition of Sql Server, than you can choose to create an index