1. A method for reducing resource consumption of a similarity index in data deduplication by a processor, comprising: representing in the similarity index only a latest generation of repository data, wherein a single latest entry is maintained for a representative value in the similarity index; applying implicit deletion in the similarity index such that a similarly index entry is not removed or overwritten until a change with associated data of the similarity index entry is detected; and maintaining a subset of bytes of the representative value in a similarity index entry.