We were unable to use the same Service Instance name when creating a service using ONAP. 

On investigating, we found that the Deletion of the service-name from the SDNC table  -sdnctl.GENERIC_RESOURCE_NAME -   failed because context-id and prefix was null.
We looked at the following DG:

• https://gerrit.onap.org/r/gitweb?p=sdnc/oam.git;a=blob;f=platform-logic/generic-resource-api/src/main/json/GENERIC-RESOURCE-API_rollback-generated-names.json;hb=7566807e10aaf852ea75293a3782407fe9ddb7bb and searched for "DELETE from GENERIC_RESOURCE_NAME WHERE type"...

SDNC invokes DG 'service-topology-operation' with 'delete' action
* followed by execution of DG 'service-topology-operation-delete'
** followed in a flow execution of DJ 'rollback-generated-names' using a flow: 1-2-4-10-13-14-16 attempting to find distinct prefix in a 'GENERIC_RESOURCE_NAME' table. 
** In a table 'GENERIC_RESOURCE_NAME' values for prefix, name_index, and context_id are missing, so that execution of a node #46 can’t be performed.

However, in the create service flow DG, we do allow to create a row in the above table (sdnctl.GENERIC_RESOURCE_NAME) even without context-Id, name_index and prefix. 

BPMN infra Microservices executes DG 'service-topology-operation' with 'assign' actions on SDNC Microservices

* followed by execution of DG 'service-topology-operation-assign' (flow goes to nodes # 17,18,20)
** followed by execution of DG 'generate-unique-name' where flow to nodes # 11, 12 is executed:
** `'insert into GENERIC_RESOURCE_NAME values ( '+ ' $generate-unique-name-input.name-table-type , $generate-unique-name-input.supplied-name , null , null, null )'


* As a result of this execution in a table sdnctl.GENERIC_RESOURCE_NAME new entry is created where prefix, name_index, and context_id are null

So now we have a 'Service instance Name' entry in GENERIC_RESOURCE_NAME table of SDNC that cannot be deleted. Because of this, we cannot reuse the same Service Instance name.

Please see the discussion on this Thread:

https://lists.onap.org/g/onap-discuss/topic/32131591?p=Created,,,20,1,0,0::relevance,,,0,0,0,0