A computing system disposed within a remote network management platform comprising: a database that contains a plurality of configuration item records corresponding to a set of computing devices disposed within a managed network, a set of software applications configured to execute on the set of computing devices, and a network-based service that is provided by execution of the set of software applications, wherein the managed network is associated with the computational instance (322, 324, 326, 328), wherein the database contains a definition of a service model that represents the set of computing devices, the set of software applications, and relationships therebetween that facilitate providing the network-based service, and wherein the service model includes a service environment (604, 606) having multiple service layers that are hierarchically-arranged within the service environment (604, 606); and one or more server devices configured to: receive, from the managed network, an indication of a change to a CI record of the plurality of CI records; store, in the database, the CI record as changed; add, to a change record table stored within the database, a change record corresponding to the change to the CI record, wherein the change record: (i) references the CI record and a service layer of the multiple service layers, and (ii) specifies a change type that is indicative of whether the change affects a topology of the service model; based on the change type, select for the service layer a service model re-computation mode from among a plurality of service model re-computation modes, wherein selecting the service model re-computation mode comprises: in response to the change type indicating that the change does not affect the topology of the service model, selecting a fast re-computation mode; and in response to the change type indicating the change does affect the topology of the service model, selecting a full re-computation mode; and re-compute the service layer of the service environment (604, 606) in accordance with the selected service model re-computation mode. a database that contains a plurality of configuration item records corresponding to a set of computing devices disposed within a managed network, a set of software applications configured to execute on the set of computing devices, and a network-based service that is provided by execution of the set of software applications, wherein the managed network is associated with the computational instance (322, 324, 326, 328), wherein the database contains a definition of a service model that represents the set of computing devices, the set of software applications, and relationships therebetween that facilitate providing the network-based service, and wherein the service model includes a service environment (604, 606) having multiple service layers that are hierarchically-arranged within the service environment (604, 606); and one or more server devices configured to: receive, from the managed network, an indication of a change to a CI record of the plurality of CI records; store, in the database, the CI record as changed; add, to a change record table stored within the database, a change record corresponding to the change to the CI record, wherein the change record: (i) references the CI record and a service layer of the multiple service layers, and (ii) specifies a change type that is indicative of whether the change affects a topology of the service model; based on the change type, select for the service layer a service model re-computation mode from among a plurality of service model re-computation modes, wherein selecting the service model re-computation mode comprises: in response to the change type indicating that the change does not affect the topology of the service model, selecting a fast re-computation mode; and in response to the change type indicating the change does affect the topology of the service model, selecting a full re-computation mode; and re-compute the service layer of the service environment (604, 606) in accordance with the selected service model re-computation mode. receive, from the managed network, an indication of a change to a CI record of the plurality of CI records; store, in the database, the CI record as changed; add, to a change record table stored within the database, a change record corresponding to the change to the CI record, wherein the change record: (i) references the CI record and a service layer of the multiple service layers, and (ii) specifies a change type that is indicative of whether the change affects a topology of the service model; based on the change type, select for the service layer a service model re-computation mode from among a plurality of service model re-computation modes, wherein selecting the service model re-computation mode comprises: in response to the change type indicating that the change does not affect the topology of the service model, selecting a fast re-computation mode; and in response to the change type indicating the change does affect the topology of the service model, selecting a full re-computation mode; and re-compute the service layer of the service environment (604, 606) in accordance with the selected service model re-computation mode. in response to the change type indicating that the change does not affect the topology of the service model, selecting a fast re-computation mode; and in response to the change type indicating the change does affect the topology of the service model, selecting a full re-computation mode; and re-compute the service layer of the service environment (604, 606) in accordance with the selected service model re-computation mode.