See how your tables join
Every connection in Settings → Admin → Data now has a Relationships section: a map of how its tables join, drawn from the keys you, dbt or the warehouse declared — and a list of the references that don't join yet, each with a link to the column to fix.
The join graph
Each table that declares a key is a box listing its primary and foreign keys; an arrow runs from every foreign key to the primary key it points at, tables on the left pointing at tables on the right. Click a table to focus its joins — the rest fades, and the Joins table below narrows to that table. On a connection with several schemas or datasets, a picker narrows the graph to one of them and what it joins to.
The graph is a canvas rather than a picture: it opens on the whole map, and you drag it to pan, and zoom with the wheel or the controls in its corner — so a schema with dozens of joined tables stays something you can read. And because it is a canvas, the map takes the room it needs: tables stand well apart, each one level with the tables it joins, and the ones that don't join anything yet are set apart below the graph rather than crowding its last column.
Below the graph, Joins lists every reference: from, to, cardinality, whether its reverse join is on, and where it comes from — the warehouse's own foreign keys, dbt, or a key you declared.
References that don't join
A foreign key that points at nothing yet, at a table the connection doesn't have, at a key the table doesn't declare, or at a key that isn't primary is drawn as a dashed line ending in ?, called out above the graph, and listed with the reason. Fix on … opens the column on its table page with the inspector on that key.
The graph reflects your unsaved edits, so you can declare the missing key on the table page, come back to see the arrow appear, and save once it joins.