5. The machine-readable storage medium of claim 1 , wherein the encode index comprise a cache-sensitive array trie index or a cache-sensitive prefix trie index.
6. The machine-readable storage medium of claim 5 , wherein the cache-sensitive array trie index comprises: storing the plurality of string values in a decode index array; propagating in preorder the plurality of string values to the shared-leaves structure via variable buffers at each cache-sensitive array trie node to populate the decode index array only once per bulk; and generating the subset of the plurality of order-preserving integer codes for the corresponding subset of the plurality of string values in parallel.