1. A method for computer-based real time modification and management of hierarchical data comprising: storing a base hierarchy that categorizes a collection of inventory including a number of consumer products into a number of levels of categories in a database management system; receiving a plurality of desired changes to the base hierarchy from a user within a graphical user interface of a computer, wherein the desired changes collectively characterize a modified hierarchy categorizing the number of consumer products, and wherein the plurality of desired changes reflect marketplace performance data of the number of consumer products; storing the plurality of desired changes logically separately from the base hierarchy as change data using a database tool, wherein each item of change data includes an instruction to add, delete, or move a node between the base hierarchy and the modified hierarchy, the instruction received from the user through a drag-and-drop operation of the node on a visual representation of one or more of the base hierarchy and the modified hierarchy displayed on the graphical user interface, wherein each item of change data is an invertible instruction with a corresponding instruction that undoes the change, and wherein an order of the change data is maintained for a plurality of items of change data; dynamically displaying a representation of the modified hierarchy to the user in the graphical user interface with a user interface tool executing on the computer by rendering the base hierarchy as modified according to each item of change data; receiving a query with respect to the modified hierarchy in the graphical user interface; and processing the query by performing the steps of: identifying an inverse for each of the plurality of desired changes, thereby identifying a plurality of inverses; using the plurality of inverses in a reverse of the order, determining a modified query with respect to the base hierarchy; and processing the modified query with respect to the base hierarchy.