supabase-cli/docs/supabase/db/pull.md

supabase-db-pull

Pulls schema changes from a remote database. A new migration file will be created under supabase/migrations directory.

Requires your local project to be linked to a remote database by running supabase link. For self-hosted databases, you can pass in the connection parameters using --db-url flag.

Optionally, a new row can be inserted into the migration history table to reflect the current state of the remote database.

If no entries exist in the migration history table, pg_dump will be used to capture all contents of the remote schemas you have created. Otherwise, this command will only diff schema changes against the remote database, similar to running db diff --linked.