Techniques for querying federations of interlinked knowledge graphs provide a great potential for scenarios in which bringing these graphs together into a central repository is not a suitable or desired option, and yet one wants to be able to answer queries or run analyses for which the data from these graphs needs to be combined with one another.
Existing work on such techniques has, by and large, assumed homogeneous federations. In practice, however, the federations may be heterogeneous in several dimensions, including the underlying data models, the schemas, and the data access interfaces. In this talk I will highlight query processing related challenges posed by such heterogeneity and report on ongoing work in our group to address these challenges.