Multi-part upload and editing of erasure-coded objects

Segments of a local range can appear multiple times in the sequence of erasure sets in a manifest without the data being duplicated. A subset of the content of an erasure set can be included in the logical object. It is not required that all erasure sets in an object use the same encoding. A manifest can indicate one or more portions of the logical object for which no data has been provided, and for which a "fill" pattern is specified. A portion of data can be inserted at any point inside the object by inserting a reference to one or more segment sets containing that data into the manifest. If the desired insertion point is within an existing segment set, then that manifest set can be "split" by incorporating two references to it, with the first specifying the range of data before the insertion point, and the second specifying the range of data after the insertion point. Many operations are thus enabled on an erasure-coded object in Object Storage such as "append", "insert," "overwrite" and "merge."