1. A method of processing information relating to the execution of instructions by a database management system, comprising: receiving an instruction; receiving execution information relating to the execution of the instruction by the database management system; comparing the instruction to one or more previously received instructions and determining whether, according to a predetermined equivalence criterion, the instruction matches one of the previously received instructions; and if the instruction matches a previously received instruction, combining the execution information with execution information relating to the matching one of the previously received instructions to produce aggregate execution information.