Patent ID: 9690790
Date: 2017-06-27
CPC Classifications: G06F

Claim:
1. A method comprising: receiving a request for a plurality of pages in a set of incrementally stored data as of a desired time; wherein the set of incrementally stored data comprises a base archive and a plurality of snapshots; wherein each snapshot corresponds to a distinct epoch of a plurality of epochs, each epoch comprising a time period after creation of the base archive; wherein each snapshot comprises: going from most-recent epoch to least-recent epoch, searching the index of each snapshot corresponding to an epoch later than creation of the base archive and no later than the desired time to identify a location of a most recent version of each page of data that was changed during the epoch; storing, in a hash table, each location of each most recent version identified in the searching step, wherein the hash table utilizes a hash function to assign each page number to a unique value, wherein the unique value determines data associated with each said page number; searching the hash table for an entry corresponding to a desired page; if an entry corresponding to the desired page is found, retrieving the data from the snapshot corresponding to the epoch identified by the entry; if an entry is not found in the hash table, retrieving the data from the base archive; and wherein the desired time is later than the creation of the base archive and wherein data in each revised version of each page in a snapshot is later than the data in each corresponding page of the base archive.