Patent ID: 8140546

Claim:
A computer system for creating an index to aggregate data in at least one tree structure including at least one node, in which each of the nodes includes one label indicating the type of the node and zero or more values, the computer system comprising: a storage device, which includes: a node ID assignment processing unit for assigning node IDs to the nodes in a post order; a first index creation processing unit for creating a first index having one or more sets of data including the node ID of each of the nodes and the values included in the node, wherein the one or more sets of data are generated for each of the labels; a second index creation processing unit for creating a second index having one or more sets of data including the node ID of each of the nodes and the node ID of a descendant node having the minimum node ID among at least one descendant node of the node, wherein the one or more sets of data are generated for each of the labels; and a third index creation processing unit for creating a third index having one or more sets of data including the node IDs of one or more nodes including specific values, wherein the one or more sets of data are generated for each of the specific values for each of the labels; wherein the first, the second, and the third index creation processing units create the index to aggregate data in the at least one tree structure including at least one node.