COSMOS CMDBf Query to SQL Mapping
MDRs and federating CMDBs support CMDBf query services, which accepts queries in CMDBf query format. The query service interprets the CMDBf query and queries the underlying data store for data. We can safely assume that no database or application would understand the CMDBf query today, as it is a new standard. So the MDR or ferderating CMDB would need to translate the CMDBf query to another query language, or invoke an appropriate method call of the application that serves the data for the MDR.
It is common to have data stored in relational databases. It is useful to come up with a set of guidelines for mapping CMDBf queries to SQL, and vice versa.
CMDBf query only supports a subset of SQL query capabilities, and there are CMDBf queries that are difficult to be done with SQL. The goal is to cover the basic queries that allows a two-way mapping between CMDBf query and SQL.
The examples below will use the following two schema definitions. These two schemas are equivalent but the CMDBf queries may be different.
Both schemas are for modeling relationships between operating system (OS) instances with computers. An operating system instance can be installed on one computer. In the first schema, the relationship is represented by the foreign key from the OS table to the Computer table. In the second schema, the relationship is represented by a separate table.