Early exit from table scans of loosely ordered and/or grouped relations using nearly ordered maps

摘要

According to embodiments of the present invention, methods, systems and computer-readable media are presented for scanning a plurality of storage regions within memory for a specified quantity of results, wherein each storage region is associated with an interval including first and second interval values indicating a value range for values within that storage region. The techniques comprise sorting the first interval values into an order, wherein the order of the first interval values determines a scanning order for the plurality of storage regions, determining a result value, wherein the result value is an upper bound, a lower bound, or is outside of the specified quantity of results, and examining the sorted first interval values and scanning corresponding individual storage regions in response to a comparison of the determined result value with the first interval value of that storage region. In some embodiments, scanning exits upon establishing that the specified quantity of results has been achieved and that a first interval value in a list of sorted first interval values is greater than the determined result value.