1. A method for processing database data in a distributed database system, wherein the distributed database system comprises a plurality of computing nodes communicatively coupled via computer networks, the method comprising: creating a plurality of different data replicas, wherein each of the data replicas is created in the following way: (a) sorting the database data according to at least two data attributes, wherein the database data is sorted differently based on the data attributes for each of the data replicas; (b) generating a row key based on the at least two data attributes; and (c) using the sorted database data with the row key as the data replica; storing different data replicas in different computing nodes; and creating an index for each of the data replicas according to its row key; wherein the at least two data attributes that are used as the basis for sorting of the database data comprise an attribute indicative of time and an attribute indicative of a device identifier; wherein the sorting of the database data of a first one of the data replicas comprises first sorting the database data by the attribute indicative of the device identifier and then sorting the database data by the attribute indicative of the time; and wherein the sorting of the database data of a second one of the data replicas comprises first sorting the database data by the attribute indicative of the time and then sorting the database data by the attribute indicative of the device identifier.