1. A computer-implemented method, comprising: receiving a database query; generating, by operation of one or more computer processors, a plurality of query plans for executing the database query; estimating one or more characteristics of energy consumption for executing each query plan; estimating one or more characteristics of time for executing each query plan; and selecting one of the plurality of query plans for executing the database query, based at least on (i) the one or more characteristics of energy consumption, (ii) the one or more characteristics of time, and (iii) a relative priority between the characteristics of energy consumption and the characteristics of time.