Rebuilding derived content

A computing device of a dispersed storage network (DSN) comprises:

• an interface;
• memory;
• and
• a processing module operably coupled to the interface and memory, wherein the processing module is operable to:
• determine whether alternate form data (AFD) exists for a data object, wherein the AFD is a content derivation of the data object;
• and
• when the alternate form data does not exist:
• identify a content derivation function in accordance with an AFD policy of the DSN, wherein the identifying the content derivation function includes selecting the content derivation function from a plurality of content derivation functions in accordance with the AFD policy regarding the data object;
• identify a portion of the data object based on the content derivation function;
• identify one or more sets of encoded data slices of a plurality of sets of encoded data slices corresponding to the portion of the data object, wherein the data object is dispersed storage error encoded to produce the plurality of sets of encoded data slices;
• generate at least a portion of the AFD based on the one or more sets of encoded data slices;
• and
• store, in accordance with a storage approach, the at least a portion of the AFD within memory of the DSN.