7. The non-transitory computer-readable storage medium of claim 6 , wherein generating the sketch further comprises: generating a set of features for the selected data chunk.
6. A non-transitory computer-readable storage medium having instructions stored therein, which when executed by a computer, cause the computer to perform operations for improving efficiency in a delta compression process, the operations comprising: selecting a data chunk to delta compress; selecting a data chunk to delta compress; generating a sketch for the selected data chunk; searching for a set of candidate data chunks using the sketch; ranking the set of candidate data chunks with at least minimum degree of similarity by location status data, wherein the location status data indicates a location and a compression status of a candidate data chunk status, wherein the location status data indicates the location and status of the candidate data chunk as in any one of a compressed in a cache status, a decompressed in a cache status, or a compressed in a data storage status, and wherein ranking the set of candidate data chunks using location status data for each candidate prefers a decompressed in a cache status over a compressed in a cache status; tie-breaking the set of candidates data chunks using degree of sketch similarity for each candidate; and delta compressing the selected data chunk with a selected candidate data chunk.