Patent ID: 8738573

Claim:
A computer-executable storage device having computer-executable instructions, which when executed perform actions, comprising: maintaining a first version of a report via a plurality of rows of a first table of a database, the rows including data associated with the report; allowing a first user and a second user to concurrently access the first version of the report, wherein the first user and the second user share the report via a same physical data; receiving a request from the second user to update the report; while maintaining the first version of the report, creating a second version of the report by, in part, actions comprising: copying at least a portion of a first row of the first table that is affected by the update to create a second row in the first table; changing data of the first or second rows to include data corresponding to the update; in response to changing data of one of the first or second row, the first row and the second row having different versions of data; and updating one or more other tables to reference rows in the first version of the report that are also included in the second version of the report, wherein the first user accesses the first version of the report, and the second user maintains accesses the second version of the report, the first version not affected by the update to the report, wherein the first user and the second user continue to share access to a same physical data of at least one unmodified segment and wherein updating one or more other tables to reference rows in the first version of the report that are also included in the second version of the report comprises updating a mapping table that maps chunks to rows of the table, the first version of the report being associated with one or more chunks, wherein updating a mapping table that maps chunks to rows of the table comprises creating a new row in the mapping table for each chunk associated with the first version of the report and associating each chunk so created with the second version of the report.