I have a very dynamic vendor who adds and deletes products daily. They provide major updates twice daily and while they don't provide inventory numbers - just "in stock" and "out of stock" every 15 minutes. Obviously, it is not feasible to update my db every 15 minutes. However, my question is, would I be better off to build a temporary single column file which contains all sku's provided from the data feed and then parse my products table and 200+ categories deleting the table after updating all applicable tables or date stamp the product table and delete any record that was not included in that days major update feed. I am leaning toward the temp file as it would reduce the overhead of the date stamp.