First thing I would like to say is I absolutely hate re-indexing manually on Magento. But as we all Magento Developers have no choice but to fix it and make client and boss happy. We encounter errors that gives more headache if we don't find the solution straight away. Sometimes I have to browse through so many magento forums pages with no luck. So, I'm going to show you how to fix this annoying magento reindexing error. When I tried to re-index products first I got this error.
I mistakenly canceled one order and spent a day to go through magento & different forums and blogs and searching for a solution and this is how i fixed myself after few tries. I am still not sure how to extend the controller so i modified the core file and made a copy so i can paste back if overwritten when upgrade or i can copy when i find the solution how to extend or override a magento controllers.
Create a file @ app\code\local\Codefight\Adminhtml\Block\Sales\Order\Grid.php
There is no easy method like adding product attribute for category yet. But we can achieve this by adding from database. You just need to deal with three tables in the database.