1. A computer-implemented method for estimating a loaded execution runtime of database query, said method comprising: receiving a database query for a database; receiving load information for said database, said database being loaded; accessing a prediction of query runtime tree built from historical query information regarding historical database queries previously executed on said database, said prediction of query runtime tree including a classifier function adjusted for an historical impact of loading of said database, said query runtime tree comprising a plurality of nodes, said classifier function for determining at least one branching path from at least one node of said plurality of nodes; and processing said database query through said prediction of query runtime tree, such that a loaded execution runtime of said database query is estimated based upon information pertaining to historical database queries similar to said database query.