Abstract: A system for integrating multiple indexed files and searching the resulting integrated indexed file. An indexed core content file, which includes a core keyword list containing core keywords, can be updated with update keywords of an update content file. The update content file is accessed and, in response, a virtual keyword list is generated. The virtual keyword list, which contains update keywords and core keywords, is created by determining a position for inserting each update keyword within the core keyword list and positions for each core keyword affected by the insertion of update keywords. An index mapping table is created for tracking the positions of the update keywords and the core keywords within the virtual keyword list. The index mapping table maps the positions of the update keywords within the virtual keyword list to the update keywords within the update content file and maps the positions of the core keywords within the virtual keyword list to the core keywords within the core keyword list.