9. The apparatus according to claim 8 , wherein the processor is configured to: determine whether the second pattern character string is to be re-created, based on the calculated ratio, and extract the partial character string from one or plurality of messages conforming to the first pattern character string among the plurality of acquired messages when a determination is made that the second pattern character string is to be re-created.
9. The apparatus according to claim 8 , wherein the processor is configured to: determine whether the second pattern character string is to be re-created, based on the calculated ratio, and extract the partial character string from one or plurality of messages conforming to the first pattern character string among the plurality of acquired messages when a determination is made that the second pattern character string is to be re-created. 10. The apparatus according to claim 9 , wherein the processor is configured to: calculate a second ratio at which at which the one or plurality of messages conform to the second pattern character string when the second pattern character string is created, determine whether the second pattern character string is to be deleted based on a difference between the first ratio and the second ratio, and delete the second pattern character string before acquiring the plurality of messages transmitted or received by the server when a determination is made that the second pattern character string is to be re-created and the second pattern character string is to be deleted.