1. A computer-implemented method for supporting migration of unstructured data stored in enterprise content management systems, comprising: generating a search for content matching at least one content search rule; receiving a list of matched documents, wherein each document in the list of matched documents is associated with at least a source repository identifier and a unique document identifier; calculating a target repository identifier and at least one metadata change instruction for each unique document identifier using at least one migration rule; and modifying metadata for the document associated with each unique document identifier using the calculated at least one metadata change instruction.