1. A computer-implemented method comprising: causing an engine to store an updatable column representation of data including a row column in a main structure and in a delta structure of an in-memory database; causing the engine to merge the delta structure into the main structure when a delta exceeds a threshold; causing the engine to sort columns of the updatable column representation according to values of the row column; causing the engine to derive an index according to the sorted columns; causing the engine to reference the index to perform an algebraic operation; and causing the engine to store a result of the algebraic operation.