I agree it's a work in progress and needs further refactoring. Looking at it, I think it pretty much contains only the logic that just displays the Database_Structure index page (or may be the logic for "Drops/deletes/etc. multiple tables if required" needs to go into separate action?). Thereafter, it can surely be further broken into some helper functions or sub-actions for readability/reuseability.

Also, it's size will further reduce once other actions like addRemoveFavoriteTablesAction are called directly, instead of, via indexAction.