1. A computer-implemented method for obtaining data from a cluster of cache nodes in a tree-based structure, the method comprising: receiving a query for data of a cache node of a partition group from a querying cache node outside the partition group, the partition group comprising one or more cache nodes of the cluster, wherein an instance of a cache node in the partition group is copied to each cache node in the partition group; copying the instance of the data of the cache nodes of the partition group to the querying cache node; and adjusting the partition group to include the querying cache node as a member of the partition group.