1. A system comprising: an object store to store a plurality of objects and corresponding object metadata properties within storage devices, each of the objects having an object id and being associated with a bucket, each of the metadata properties having a key and an corresponding value; a secondary index to map ones of the object metadata properties to ones of the object ids; a query parser to receive a query from a query source and to parse the received query into a query parse tree, the received query having a bucket id identifying a bucket within the object store and having a predicate involving one of the object metadata keys; a query executor to determine ones of the object ids from the secondary index using the bucket id and the object metadata keys involved in the query predicate, and to retrieve ones of the object metadata properties from the object store using the determined object ids to generate a query result set stream; and a query formatter to generate a response to the query source based upon the query result set stream.