1. A computer storage medium having computer-executable instructions, which when executed perform actions, comprising: obtaining a change to a first schema, the first schema being mapped to a second schema via a set of mappings, the first schema having a plurality of types arranged in a hierarchy, the change involving at least one affected type of the types; analyzing the hierarchy to determine a mapping pattern by: determining two or more of the types that are more similar to the at least one affected type than any other of the types, similarity being determined according to the following rules: a type is most similar to its siblings, a first type and a second type, neither a descendant of the other, are more similar to each other than to a least common ancestor of the first and second types, and if a first type is a descendant of a second type, then the first type is more similar to any descendants of the second type than to the second type, but more similar to the second type than to any ancestors, siblings or descendents of siblings of the second type; and determining a mapping pattern between the two or more types and elements in the second schema; and based on the mapping pattern and the change, updating the set of mappings and the second schema.