I have lost more afternoons than I would like to admit on this exact problem: a seed script that ran cleanly yesterday now crashes on its first INSERT, and the error message tells you something you already knew, namely that you have a chicken-and-egg dependency between two tables. SQL ERROR: insert or update on table "users" violates foreign key constraint "users_organization_id_fkey"DETAIL: Key (organization_id)=(1) is not present in table "organizations". The natural next move is to reorder the inserts, putting organizations first, except that organizations.owner_user_id is NOT NULL REFERENCES users(id), which means you cannot insert an organization without a user that does not exist yet. You are looking at a foreign-key cycle, and no ordering of plain INSERT statements can satisfy every NOT NULL REFERENCES at row-insertion time. The rest of this article walks through three working strategies for seeding a Postgres database that contains FK cycles, plus a decision table for picking the right one. Examples assume Postgres 18, which is the current stable as of mid-2026, but most of the reasoning ports cleanly to earlier versions and to other RDBMSes, with the caveats called out where they matter.