Patent ID: 7395278

Claim:
A method for providing a database view comprising transaction-consistent data reflecting the contents of a database at a specific point in time, said database comprising data elements and associated with a transaction log, said transaction log comprising active transactions and inactive transactions, said database view comprising difference storage for storing prior versions of at least one of said data elements from said database, said method comprising: determining a split point on said transaction log corresponding to said point in time; identifying each transaction on said transaction log prior to said split point which performs modifications on said database; storing each of said modifications in said difference storage; maintaining a side page table that comprises information regarding whether each data element is stored in the difference storage and whether each data element is allocated in the difference storage; identifying each active transaction on said transaction log prior to said split point; undoing any corresponding modifications in said difference storage; storing said difference storage; accepting a request for a specific data element in said database view; determining if data is stored in a location corresponding to said specific data element in said difference storage: responding to said request by reading said difference storage if data is stored in a location corresponding to said specific data element in said difference storage: and responding to said request by reading said database if data is stored in a location corresponding to said specific data element in said difference storage.