Methods, systems, and computer-readable storage media for receiving a plurality of source hierarchical schemas, processing the source hierarchical schemas to generate a merged graph, which is comprising a plurality of merged nodes, each merged node being provided based on one or more nodes from at least two of the source hierarchical schemas, determining and resolving using conflicts in the merged graph to generate a conflict-free merged graph, wherein resolving comprises splitting one or more merged nodes into respective sub-sets of merged nodes, defining and processing a constraints satisfaction problem (CSP) to generate a plurality of mediated hierarchical schemas (MHSs), each MHS being a solution to the CSP, identifying an MHS of the plurality of MHSs as an optimum MHS, wherein a canonical hierarchical schema (CHS) is provided as the optimum MHS, and storing the CHS as a computer-readable document in a computer-readable memory.