ALTER TABLE employees
ADD COLUMN IF NOT EXISTS profile_unavailable_streak INTEGER NOT NULL DEFAULT 0;

ALTER TABLE employees
ADD COLUMN IF NOT EXISTS last_profile_check_at TIMESTAMPTZ;

CREATE TABLE IF NOT EXISTS employee_profile_urls (
  id SERIAL PRIMARY KEY,
  employee_id INTEGER NOT NULL REFERENCES employees(id) ON DELETE CASCADE,
  url TEXT NOT NULL,
  first_seen_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  last_seen_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  CONSTRAINT uq_employee_profile_urls_employee_url UNIQUE (employee_id, url)
);

CREATE INDEX IF NOT EXISTS ix_employee_profile_urls_employee_id
  ON employee_profile_urls (employee_id);