Methods, systems, and articles of manufacture for indexing annotations made for a variety of different type (i.e., heterogeneous) data objects are provided. A set of parameters uniquely identifying an annotated data object may be converted to an index comprising a set of index values, each corresponding to a column in a homogeneous index table. In order to accommodate the indexing of heterogeneous data objects, a mapping may be provided for each different type (or classification) of data object that may be annotated, that defines how the identifying parameters of that type will be mapped to the columns of the homogeneous index table.