MySQL add index on relatively big table (InnoDB)

Question

I have a relatively big InnoDB table (~20m rows) and I want to add an index to a column.

The table is being read from and written to frequently, so I want the table to still be usable while the index is being added.

How can I achieve this?

I currently see two options:

• Just blindly add the index and pray nothing will happen
• Creating a replica table with the structures + the index, add the data from the original table and then rename the replica to the original and dropping the original.

Is there a better way?

Thanks :)

MySQL version: 5.0.51

Answer 1

2nd option would be great but how can you achieve this? I recommend MySQL Workbench