1. A method of maintaining catalog data stored in a system product data file, the method executed by one or more computing devices and comprising: receiving, by at least one of the one or more computing devices, a customer product portfolio file that identifies products for which product data is requested by one or more customers, the product data being suitable for use in an electronic catalog, the customer product portfolio file including a manufacturer SKU uniquely identifying a product for which product data is requested for use in an electronic catalog, a customer SKU uniquely identifying a product that corresponds to one of the customers, and a manufacturer identifier identifying a manufacturer of a product for which product data is requested, each of the customers being a manufacturer, retailer, or distributor products for which product data is requested by the customer in the customer product portfolio file; and mapping, by at least one of the one or more computing devices, the customer product portfolio file to the system product data file such that each product for which product data is not in the system product data file is identified, thereby identifying product for which product data is requested but has not been previously obtained and stored in the system product data file, wherein mapping the customer product portfolio file includes: determining, by at least one of the one or more computing devices, whether the customer SKU in the customer product portfolio file is new, the customer SKU being new if the customer SKU is not identified in the system product data file; and creating, by at least one of the one or more computing devices, a new system SKU based at least in part on a determination that the customer SKU is new, wherein the new system SKU is mapped in the system product data file to the customer SKU.