Patent ID: 8219587

Claim:
A method implemented by a computing apparatus for tracing, on the basis of a key, an index created using a tree structure in order to access data stored on a computer-readable article of manufacture, the tree structure including one root node and at least one leaf node which, when at least two leaf nodes are present, (i) includes information that represents a relation with a neighboring leaf node and (ii) is bidirectionally linked to the neighboring leaf node, the method comprising the steps of: searching the tree structure to reach a target node that can be associated with the key without acquiring a lock on the root node and on any internal node in the tree structure; setting the target node as a current node when the target node is a leaf node; moving the search to a node at a lower layer in the tree structure when the target node is an internal node by tracing an edge in the tree structure to reach a leaf node without acquiring a lock on any internal node and setting the leaf node as the current node; and associating the key with the leaf node specified as the current node by acquiring a lock on the leaf node specified as the current node, thereby accessing data stored on the computer-readable article of manufacture by the computing apparatus.