1. A computer-implemented method to determine error propagation for a query optimizer component of a database management system (DBMS) for a database, the method comprising: receiving a database query specifying one or more query conditions; determining a measure of actual selectivity of the one or more query conditions specified in the received database query; determining a measure of estimated selectivity of the one or more query conditions specified in the received database query; and determining a measure of estimated deviation between the determined measure of actual selectivity and the determined measure of estimated selectivity; wherein the query optimizer component, when executed by one or more computer processors, is configured to perform at least one of: generating a first query execution plan based on the received database query and based further on the determined measure of estimated deviation; and selecting, based on the determined measure of estimated deviation, the first query execution plan from a plurality of distinct query execution plans generated based on the received database query.