Various embodiments provide a copy-on-write data frame (CoW-DF) that permits lightweight copies of a data frame, where the copies comprise memory allocation for only changed portions of a data frame. A CoW-DF may have semantics of a data frame, and a CoW-DF may appear and behave like a traditional data frame copy, while on the backend of a CoW-DF, only data differences created by modifications to a data frame may be maintained, rather than whole copies of a modified data frame. For various embodiments, the CoW concept is applied to other types of data structures, such as a column, a row, or a data frame value.