text: --
  -- _versions
  --
  CREATE SEQUENCE _sq_versions;
  
  CREATE TABLE _versions
  (
    id int NOT NULL DEFAULT nextval('_sq_versions'),
    CONSTRAINT _pk_versions PRIMARY KEY (id),
    created_at timestamptz NOT NULL DEFAULT CURRENT_TIMESTAMP,
    migration text NOT NULL
  );
  
  CREATE UNIQUE INDEX _ux_versions_migration
  ON _versions (migration);
  
  