This is where the OpenArk tools come to the rescue. The set of free python tools makes many time consuming DBA tasks easy as could be. I’m only going to cover the oak-online-alter-table function, but there is plenty of in-depth instruction for the other functions on the the OpenArk website.
Here is the simple line by line installation
Altering the old way
Altering with OpenArk
Live Status of the Process
This is one of the biggest benefits of using OpenArk – you get a live status report telling you exactly what percentage of the move is complete. Anyone who has done manual altering knows how difficult it is to have no sense of the progress.
How it works
The tool uses a concept called “Ghosting”. A second table with the new schema is created. The data is copied over to the new table and any modifications to the data which occurred during the copy process are then executed on the new table to make sure it’s up to date. Then the new table is then renamed to the original tables name, and the old table is then dropped. With all of the steps required it’s easy to see the value in a tool that takes care of everything.