US Patent 9459968 Single index to query multiple backup formats

The disclosed techniques include generation of a single index table when backing up data in a first backup format to a backup storage system that uses a second backup format. Using the single index table, a query for a data item can be answered by searching the single index table. The single index table avoids having to search through multiple index tables, each corresponding to a different backup format that may be used for backing up the searched data item.