Abstract: A virtual merge of update data into a large ordered data set, such as an encyclopedia database. The ordered set is stored on a client, and includes original indices defined by a server, which also defines an initial index for each entry to be added to the ordered set as an update, where each initial index corresponds to a position that the entry would occupy in the ordered set if the entry were considered alone. An exception table is created by incrementing the initial indices by a number of entries to be added prior to a current entry and by decrementing for prior deleted entries. The client creates a dynamically ordered set from at least a portion of the large ordered set by analogously incrementing and/or decrementing the original indices. The dynamically ordered set and exception table define a virtually merged database that the client can access dynamically.