Diagrams, snapshots and comparing schemas

6.1 Schema diagrams#

The Diagram button next to a schema in the menu draws its tables and the foreign keys between them.

1 finds a table by name and centers it.
2 switches between full columns and table names only — the better view for a large schema.
3 saves the diagram as SVG, or PNG while it is small enough.

Drag the canvas to pan and pinch to zoom. Drag a table by its card to move it; Tabellum remembers where you put it. A tap on a table selects it and lights up its foreign keys, and the Inspect page shows it; a tap on empty canvas clears the selection.

6.2 Snapshots#

A snapshot is a schema’s structure — tables, columns, keys, indexes, views, functions — saved as a file in snapshots/, without any rows. Take one with Save schema snapshot in the palette or the connection’s menu — before a risky change, for example — then compare against it later, or bring a database back to it.

6.3 Comparing two schemas#

Compare schemas (in the palette or a connection’s menu) compares two sides: the one to migrate 1 and the one to reach 2. Each side is a connection as it is now or a saved snapshot.

The result lists every object as added, dropped, changed or the same, with what changed in each.

What differs between yesterdays snapshot and the database — What differs between yesterday’s snapshot and the database

Migration 2 opens the SQL that makes the left side match the right in a new tab. It runs only when you run it, through the approval dialog. Drops are left out unless Include drops 1 is on.