US Patent 7428524 Large scale data storage in sparse tables

Each of a plurality of data items is stored in a table data structure. A row identifier and column identifier are associated with each respective data item, and each respective item is stored at a logical location in the table data structure specified by its row identifier and column identifier. A plurality of data items is stored in a cell of the table data structure, and a timestamp is associated with each of the plurality of data items stored in the cell. Each of the data items stored in the cell has the same row identifier, the same column identifier, and a distinct timestamp. In some embodiments, each row identifier is a string of arbitrary length and arbitrary value. Similarly, in some embodiments each column identifier is a string of arbitrary length and arbitrary value.