In previous versions of Tableau, the physical layer was the only layer in the data model. You can think of it as the Join/Union canvas. The physical layer of the data model is where you can combine data using joins and unions. You do not need to specify join types for relationships during analysis Tableau automatically selects the appropriate join types based on the fields and context of analysis in the worksheet. When you combine data from multiple tables, each table that you drag to the canvas in the logical layer must have a relationship to another table. You can also think of it as the Relationships canvas, because you combine tables here using relationships instead of joins. The top-level view that you see of a data source is the logical layer of the data model. Physical tables are merged into a single, flat table that defines the logical table Logical tables remain distinct (normalized), not merged in the data source Level of detail is at the row level of merged physical tables Level of detail is at the row level of the logical table Logical tables are like containers for physical tablesĭouble-click a logical table to see its physical tables Physical tables can be joined or unioned to other physical tables Logical tables can be related to other logical tables Tables that you drag here are called physical tables Tables that you drag here are called logical tables Join/Union canvas in the Data Source page Relationships canvas in the Data Source page In this example, the Book logical table is made of three, joined physical tables (Book, Award, Info). Physical tables can be combined using joins or unions. They act like containers for physical tables.ĭouble-click a logical table to open it and see its physical tables. Logical tables can be combined using relationships (noodles). The top-level view of a data source with multiple, related tables. Double-click a logical table to view or add joins and unions. Think of the physical layer as the Join/Union canvas in the Data Source page. Each logical table contains at least one physical table in this layer. You combine data between tables at the physical layer using joins (Link opens in a new window) and unions. For more information, see Use Relationships for Multi-table Data Analysis. Think of this layer as the Relationships canvas in the Data Source page. You combine data in the logical layer using relationships (or noodles). The default view that you first see in the Data Source page canvas is the logical layer of the data source.Or it can be more complex, with multiple tables that use different combinations of relationships, joins, and unions. A data model can be simple, such as a single table. The tables that you add to the canvas in the Data Source page create the structure of the data model. You can think of a data model as a diagram that tells Tableau how it should query data in the connected database tables. Every data source that you create in Tableau has a data model.
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