15. One or more non-transitory computer-readable media storing instructions that, when executed by one or more computing devices, cause: accessing metadata items that specify at least structural constraints on data objects within a data repository, the metadata items being separate from the data objects for which the metadata items specify the structural constraints; generating an index, the index mapping the metadata items to terms associated with the metadata items; generating a graph describing relationships between each of the metadata items; receiving a search request comprising at least one or more search terms; based on the one or more search terms and the index, locating a candidate set of the metadata items; performing a link analysis of the graph to determine a relationship score for each particular metadata item in at least the candidate set of metadata items; for each particular metadata item in the candidate set of the metadata items, calculating a ranking score based at least on the relationship score for the particular metadata item; generating a ranked result set based on comparing the ranking scores for the candidate set of metadata items, the ranked result set including at least one metadata item in the candidate set; providing information indicating the ranked result set in response to the search request; wherein the method is performed by one or more computing devices.
15. One or more non-transitory computer-readable media storing instructions that, when executed by one or more computing devices, cause: accessing metadata items that specify at least structural constraints on data objects within a data repository, the metadata items being separate from the data objects for which the metadata items specify the structural constraints; generating an index, the index mapping the metadata items to terms associated with the metadata items; generating a graph describing relationships between each of the metadata items; receiving a search request comprising at least one or more search terms; based on the one or more search terms and the index, locating a candidate set of the metadata items; performing a link analysis of the graph to determine a relationship score for each particular metadata item in at least the candidate set of metadata items; for each particular metadata item in the candidate set of the metadata items, calculating a ranking score based at least on the relationship score for the particular metadata item; generating a ranked result set based on comparing the ranking scores for the candidate set of metadata items, the ranked result set including at least one metadata item in the candidate set; providing information indicating the ranked result set in response to the search request; wherein the method is performed by one or more computing devices. 17. The one or more non-transitory computer-readable media of claim 15 , wherein the instructions, when executed by the one or more computing devices, further cause: for each particular metadata item in the candidate set of the metadata items, determining an instance frequency score based at least in part on how many of the data objects in the data repository are instances of the particular metadata item; wherein calculating the ranking score for each particular metadata item is further based on the instance frequency score for the particular metadata item.