Dimensions and Grouping Function are two optional components while creating the Monitoring Query Language (MQL) expressions in the OCI Monitoring service. Dimensions are key-value pairs that provide additional information about a metric, such as region, compartment, or resource type. Grouping Function is a function that aggregates metric data across one or more dimensions, such as sum, count, or average. The other options are required components for MQL expressions. Reference: [Dimensions], [Grouping Function]