Changing Join Types

Arcadia Enterprise supports four basic types of column connections, otherwise known as joins: inner, left, right, and outer joins.

Briefly, here are the descriptions of the four join types:

• In an inner join, the most common type, rows in the result set contain the requested columns from the both tables for all combinations of rows where the selected columns of the tables have identical values.
• In a left join, the result set contains all rows from the left-hand table, and the matching data from the right table. Whenever no matching data is available on the right side of the join, the corresponding columns in the result set have the value NULL.
• In a right join, the result set contains all rows from the right-hand table, and the matching data from the left table. Whenever no matching data is available on the left side of the join, the corresponding columns in the result set have the value NULL.
• An outer join returns all rows from both tables. Whenever no matching data is available on one of the sides of the join, the corresponding columns in the result set have the value NULL.
• A special case, left outer join, supports join elimination in datasets that contain more than one table. By default, this setting is on, but it can be disabled. See Join Elimination.

The following steps demonstrate how to change the join type.

1. Navigate to the Data Model page of the dataset.

2. Click Edit Data Model to edit the data model.

   

3. Click the (link) icon that represents the connection that must be changed.

   

4. The Join Details modal window appears.

5. In the Join Details modal window, select an alternate join type.

   For example, instead of the default Left join, select Right join.

   

6. Click outside the Join Details modal window. Or click Edit Join Details.

7. Click Save.