1. A method for caching database usage statistics regarding a database, the database having a plurality of database objects, the method comprising: storing, by each of a plurality of processing modules configured in a hierarchical structure, information regarding accesses to a subset of the database objects by the respective processing module in an intermediate cache, wherein each of the processing modules has at least one processing module configured as a parent processing module or a child processing module; iteratively forwarding and merging intermediate caches of processing modules of a lower level of the hierarchical structure to a processing module at a higher level of the hierarchical structure; receiving, by a root processing module with no parent processing module, at least one merged intermediate cache; merging the received merged intermediate cache with an intermediate cache of the root processing module to produce a final cache of information regarding accesses to the database objects; and generating, by the root processing module, an object access counts data structure that comprises data blocks each respectively comprising entries of access counts of database objects accessible on a per processing module basis.