1. A method of data indexing by a tracked resource set client, comprising: sending a plurality of requests for a representation of a state of a plurality of resource sets by the tracked resource set client to a plurality of servers, each server storing at least one of the plurality of resource sets and each resource set including a plurality of resources; receiving, as the representation of the state of the plurality of resource sets, a plurality of tracked resource sets in response to the plurality of requests, each tracked resource set corresponding to one of the plurality of resource sets and identifying the plurality of resources of that one resource set based on rules of linked data; aggregating the plurality of tracked resource sets in a data index that is part of the tracked resource set client; and periodically executing an incremental update procedure by the tracked resource set client, wherein the tracked resource set client has a local replica of each of the plurality of resource sets as of a sync point event and a change log portion that describes a plurality of change events of the plurality of resources, the sync point event being one of a plurality of events that are recorded to configure an undo operation during a server roll-back, wherein the incremental update procedure includes sending a request to learn a current state of the change Log and find the sync point event and: processing, when the sync point event is located, the plurality of change events for the data index after the sync point event from most recent to least recent and making corresponding changes to the local replica, and performing, when the tracked resource set client is unable to find the sync point event the server rollback to an earlier state, wherein the tracked resource set client searches through the change log portion from a most recent to a least recent to find the sync point event.