We already have RDS instance used by Artifactory, and want to deploy Xray. We would like to use the same RDS instance if possible. Configuring the same SQL url/username/password details in for the Xray deployment produced this error:
2021-04-26T16:58:36.852Z [jfxr ] [ERROR] [ ] [sql_layer:253 ] [main ] Failed to Initialize xray DB tables: pq: column "name" does not exist
There should not be a problem sharing the same DB instance. You should have a dedicated DB schema for each product. The error you got might be related to resources with similar names.
See Artifactory setup and Xray setup.
In the case of Kubernetes, there is a Helm chart to install the whole JFrog Platform using a single PostgreSQL server. You can see how it uses a single setup script to prepare each app's DB schema.