1. A method for determining rule predicates to be materialized, comprising: obtaining a dependency graph of rule predicates without strongly connected sub-graph, wherein the dependency graph indicates dependency among the rule predicates; calculating an update frequency of nodes in the dependency graph; calculating a query frequency of nodes in the dependency graph; calculating a runtime query cost value and a materialization cost value of the nodes based on the query frequency and the update frequency; and determining at least one node to be materialized based on the runtime query cost value and the materialization cost value, wherein a given one of the rule predicates, corresponding to the at least one node to be materialized, comprises the rule predicate to be materialized.