A system and method compute, store and use relativity measures between events in datasets where the measures are stored in a relational memory for querying. From user data and e-commerce shopping session data, relativity measures are computed for a plurality of subsets of data attributes of the user data and session data, each subset comprising two or more data attributes. The relativity measures individually or when combined represent conditional relativities between a set of events within the session data. Only the relativity measures are stored to the relational memory. The measures may be queried for results and applied to the e-commerce service (e.g. to determine which specific product data to present or an order of the presentation of the specific product data). The relativity measures may be computed only for pre-selected relations between particular data attributes which give desired trends and insights into user shopping using the e-commerce service.