he nova_api dn table request specs, the following is spec value for an instance in server groups:
{"nova_object.version": "1.8", "nova_object.changes": ["requested_destination", "instance_uuid", "retry", "num_instances", "pci_requests", "limits", "availability_zone", "force_nodes", "image", "instance_group", "force_hosts", "numa_topology", "ignore_hosts", "flavor", "project_id", "security_groups", "scheduler_hints"], "
nova_object.name": "RequestSpec", "nova_object.data": {"requested_destination": null, "instance_uuid": "0cc6b190-73c7-4f97-8ec9-86c58ffadf2d", "retry": null, "num_instances": 2, "pci_requests": {"nova_object.version": "1.1", "nova_object.changes": ["requests"], "
nova_object.name": "InstancePCIRequests", "nova_object.data": {"requests": []}, "nova_object.namespace": "nova"}, "limits": {"nova_object.version": "1.0", "nova_object.changes": ["vcpu", "memory_mb", "disk_gb", "numa_topology"], "
nova_object.name": "SchedulerLimits", "nova_object.data": {"vcpu": null, "memory_mb": null, "disk_gb": null, "numa_topology": null}, "nova_object.namespace": "nova"}, "availability_zone": "nova", "force_nodes": null, "image": {"nova_object.version": "1.8", "nova_object.changes": ["status", "name", "container_format", "created_at", "disk_format", "updated_at", "id", "min_disk", "min_ram", "checksum", "owner", "properties", "size"], "
nova_object.name": "ImageMeta", "nova_object.data": {"status": "active", "created_at": "2021-10-05T13:53:07Z", "name": "centos7-05102021", "container_format": "bare", "min_ram": 0, "disk_format": "qcow2", "updated_at": "2021-10-05T13:53:25Z", "id": "a04131be-7b16-4a0b-bc38-b77428259ec8", "min_disk": 0, "checksum": "db51c6c23e77ac4cde8617070e640e1d", "owner": "0e760ccde5d24af5a571de40220fbf80", "properties": {"nova_object.version": "1.19", "nova_object.changes": ["hw_qemu_guest_agent", "os_type", "os_require_quiesce", "hw_disk_bus"], "
nova_object.name": "ImageMetaProps", "nova_object.data": {"hw_qemu_guest_agent": true, "os_type": "linux", "hw_disk_bus": "virtio", "os_require_quiesce": true}, "nova_object.namespace": "nova"}, "size": 4033413120}, "nova_object.namespace": "nova"}, "instance_group": {"nova_object.version": "1.10", "nova_object.changes": ["hosts", "members"], "
nova_object.name": "InstanceGroup", "nova_object.data": {"policies": ["soft-anti-affinity"], "project_id": "0e760ccde5d24af5a571de40220fbf80", "user_id": "5134ed3b93284af5ba2f05d7361edf53", "uuid": "2938ef43-9fbc-4f04-aa3b-72144e343558", "deleted": false, "created_at": "2022-03-31T08:52:19Z", "updated_at": null, "hosts": null, "members": null, "deleted_at": null, "id": 67, "name": "topolino"}, "nova_object.namespace": "nova"}, "force_hosts": null, "numa_topology": null, "ignore_hosts": null, "flavor": {"nova_object.version": "1.2", "
nova_object.name": "Flavor", "nova_object.data": {"disabled": false, "root_gb": 40, "description": null, "flavorid": "3", "deleted": false, "created_at": "2017-12-20T15:58:13Z", "ephemeral_gb": 0, "updated_at": null, "memory_mb": 4096, "vcpus": 2, "extra_specs": {}, "swap": 0, "rxtx_factor": 1.0, "is_public": true, "deleted_at": null, "vcpu_weight": 0, "name": "m1.medium"}, "nova_object.namespace": "nova"}, "project_id": "0e760ccde5d24af5a571de40220fbf80", "security_groups": {"nova_object.version": "1.1", "nova_object.changes": ["objects"], "
nova_object.name": "SecurityGroupList", "nova_object.data": {"objects": [{"nova_object.version": "1.2", "nova_object.changes": ["uuid"], "
nova_object.name": "SecurityGroup", "nova_object.data": {"uuid": "4d2fdd79-0f6c-4c26-a87b-a76b5d12901e"}, "nova_object.namespace": "nova"}]}, "nova_object.namespace": "nova"}, "scheduler_hints": {"group": ["2938ef43-9fbc-4f04-aa3b-72144e343558"]}}, "nova_object.namespace": "nova"}
{"nova_object.version": "1.8", "nova_object.changes": ["requested_destination", "instance_uuid", "retry", "num_instances", "pci_requests", "limits", "availability_zone", "force_nodes", "image", "instance_group", "force_hosts", "numa_topology", "ignore_hosts", "flavor", "project_id", "security_groups", "scheduler_hints"], "
nova_object.name": "RequestSpec", "nova_object.data": {"requested_destination": null, "instance_uuid": "8c0c44c3-c00a-41ec-bf23-a427d99de2b3", "retry": null, "num_instances": 1, "pci_requests": {"nova_object.version": "1.1", "nova_object.changes": ["requests"], "
nova_object.name": "InstancePCIRequests", "nova_object.data": {"requests": []}, "nova_object.namespace": "nova"}, "limits": {"nova_object.version": "1.0", "nova_object.changes": ["vcpu", "memory_mb", "disk_gb", "numa_topology"], "
nova_object.name": "SchedulerLimits", "nova_object.data": {"vcpu": null, "memory_mb": null, "disk_gb": null, "numa_topology": null}, "nova_object.namespace": "nova"}, "availability_zone": "nova", "force_nodes": null, "image": {"nova_object.version": "1.8", "nova_object.changes": ["min_disk", "status", "min_ram", "properties", "size"], "
nova_object.name": "ImageMeta", "nova_object.data": {"status": "active", "min_disk": 0, "min_ram": 0, "properties": {"nova_object.version": "1.19", "nova_object.changes": ["hw_qemu_guest_agent", "os_type", "os_require_quiesce", "hw_disk_bus"], "
nova_object.name": "ImageMetaProps", "nova_object.data": {"hw_qemu_guest_agent": true, "os_type": "linux", "hw_disk_bus": "virtio", "os_require_quiesce": true}, "nova_object.namespace": "nova"}, "size": 42949672960}, "nova_object.namespace": "nova"}, "instance_group": null, "force_hosts": null, "numa_topology": null, "ignore_hosts": null, "flavor": {"nova_object.version": "1.2", "
nova_object.name": "Flavor", "nova_object.data": {"disabled": false, "root_gb": 40, "description": null, "flavorid": "3", "deleted": false, "created_at": "2017-12-20T15:58:13Z", "ephemeral_gb": 0, "updated_at": null, "memory_mb": 4096, "vcpus": 2, "extra_specs": {}, "swap": 0, "rxtx_factor": 1.0, "is_public": true, "deleted_at": null, "vcpu_weight": 0, "id": 12, "name": "m1.medium"}, "nova_object.namespace": "nova"}, "project_id": "0e760ccde5d24af5a571de40220fbf80", "security_groups": {"nova_object.version": "1.1", "nova_object.changes": ["objects"], "
nova_object.name": "SecurityGroupList", "nova_object.data": {"objects": [{"nova_object.version": "1.2", "nova_object.changes": ["uuid"], "
nova_object.name": "SecurityGroup", "nova_object.data": {"uuid": "4d2fdd79-0f6c-4c26-a87b-a76b5d12901e"}, "nova_object.namespace": "nova"}]}, "nova_object.namespace": "nova"}, "scheduler_hints": {}}, "nova_object.namespace": "nova"}
As you can note some keys have not values in second case, for example scheduler_hints.