Dimensions let you explore your data, providing various levels of breakdown or grouping in your reports.
Bright Analytics' report engine let you define 2 types of dimension:
Simple Dimensions, which directly map to a specific field in a data source.
Mapped dimensions, which join a field in your data sources to a meta/lookup table.
Creating a Simple dimension
Imagine you have a data source which contains a column with device type and you want to be able to run reports which break the data in this datasource down by device type.
Create a new dimension in the report engine dimension tree by right-clicking on a folder in the Dimension tree to create a new dimension.
Click on your newly created dimension and click the '+' as below:
You will be presented with a list of data sources : pick the table you want to be able to report from with this new dimension. Once you've picked a datasource, select a field and click save. You'll also be able to see all the new compatibilities that your dimensions will have with metrics.
You will then be taken back to the Dimension overview screen and should now see a mapping to the datasource you just selected:
You can add multiple tables if your datasource has so.
Don't forget to hit commit changes at the top of the page!
For information on how to map dimensions using a lookup table please read this article.