3. The machine-readable storage medium of claim 1 , wherein the operations further comprise: rewriting a string value from the plurality of string values in an equality-predicate or in a range-predicate with a corresponding integer code from the plurality of order-preserving integer codes; and rewriting a string prefix of a prefix-predicate with corresponding integer code ranges from the plurality of order-preserving integer codes.
1. A machine-readable storage medium tangibly storing machine-readable instructions thereon, which when executed by a machine, cause the machine to perform operations comprising: propagating a plurality of string values to a compressed leaf data of a shared-leaves structure of a dictionary via an encode index; obtaining a plurality of order-preserving integer codes for the plurality of string values via an lookup operation; if a subset of the plurality of order-preserving integer codes was not found during the obtaining, inserting a subset of the plurality of string values for which the subset of the plurality of order-preserving integer codes was not found into the shared-leaves structure; generating the subset of the plurality of order-preserving integer codes for a corresponding subset of the plurality of string values; and providing a list of the plurality of order-preserving integer codes, the list including the generated subset of the plurality of order-preserving integer codes.