Systems and methods for enforcing the idempotent mode of executing commands triggered by complex event processing. An example method may comprise: receiving, by a processing device, an event data item comprising a value of a state variable; applying an event processing rule to the event data item, by evaluating a conditional statement comprising the value of the state variable, to generate an event processing command; producing a command identifier identifying the event processing command; and responsive to failing to insert the command identifier into a hash table employed for storing identifiers of executed commands, discarding the event processing command.