Provided are, among other things, systems, methods and techniques for managing associations between keys and values within a computer processing system. In one exemplary implementation, requests to store associations between keys and data values corresponding to the keys are input, and the associations are stored in entry nodes within a data structure represented as a hash-based directed acyclic graph (HDAG). Upon receipt of a data value request and accompanying request key, together with satisfaction of any additional access criterion, a return data value corresponding to the request key automatically is provided, the return data value having been generated based on at least one of the associations that involve the request key.