1. A method comprising: storing identifier information and metadata information for an entity definition, the entity definition representing an entity that performs a service, wherein the service is represented by a stored service definition that associates definitions for one or more entities that perform the service, the service having a key performance indicator (KPI) defined by a KPI search query that derives a value from machine data identified in the entity definitions, thereby transforming the machine data to the value which indicates how the service is performing at a point in time or during a period of time; executing a search query, including determining that an event satisfies a selection criterion of the search query, wherein the determining includes matching the selection criterion of the search query with the metadata information of the entity definition and matching the identifier information of the entity definition with machine data of the event; and storing a search query result reflective of said determining in computer memory; wherein the method is performed by a computer system comprising one or more processing devices coupled to the computer memory.