ALTER TABLE chat_attachments
  ADD COLUMN gate_file_id text;

ALTER TABLE chat_attachments
  ALTER COLUMN object_key DROP NOT NULL;

ALTER TABLE chat_attachments
  ADD CONSTRAINT chat_attachments_gate_file_id_key UNIQUE (gate_file_id);

ALTER TABLE chat_attachments
  ADD CONSTRAINT chat_attachments_gate_file_id_format_check
  CHECK (gate_file_id IS NULL OR gate_file_id ~ '^file-[A-Za-z0-9_-]{1,128}$');

ALTER TABLE chat_attachments
  ADD CONSTRAINT chat_attachments_storage_reference_check
  CHECK (gate_file_id IS NOT NULL OR object_key IS NOT NULL);