Data Sources
A dashboard agent gets the data that it renders on a dashboard from a data source. The type of data source currently implemented is an OQL query against the metric data stored in the cache or backing store (depending on configuration).
You design a data source query so that it returns (and optionally filters) relevant metric data, which is then rendered on dashboard components. The data source query executes whenever instances of the specified metric are added or updated, and all Dashboard components using those metrics are updated accordingly.
You can use one data source for rendering multiple dashboard components (such as charts). Chart configuration settings can use the data provided by the data source in different ways.
Conditions are Optional
In the data source query, conditions are optional. If you do not specify a condition, the data source returns all data in all rows in the database table for the metric specified in the from clause. In other words, all instances of the metric, stored in the cache or backing store (depending on configuration).
If you specify a condition, the data source filters the data. If you specify multiple conditions, the query selects only the rows that satisfy all the conditions. Conditions can be parameterized so that Dashboard users can customize their charts.