Data source: A data source defines where the database tables reside. They usually point to a table within a schema in a database.
Schema - A representation of the structure of a database, think of a blueprint for how the database is actually constructed.
Foreign Key: A foreign key is a column or group of columns in a relational database table that provides a logical link between data in two tables. Foreigns keys act as cross-references between tables because they reference the primary key in the other table.
Primary Key: Primary keys uniquely identify each record in a table. They must be unique and cannot be NULL.
Data Model: In more general terms, a data model is a visual representation that organizes elements of data and standardizes how they relate to one another. A model in Transform is the full representation of the configurations of your data sources that you commit to Transform. This includes all data sources and metrics. Each time you make a change to your data source configuration or metrics in Transform, you are creating a new version of the Transform Model.
Semantic Layer: A semantic layer creates a guide for complex data to be laid out into more familiar business terms such as revenue, product usage, or total sales, so that end users can access the data in a gated, systematic way. In doing so, it maps out the abstraction of relationships across tables within a relational db (influenced by the data model), so that non-technical folks don’t have to dive into the nitty gritty of a data warehouse.