def get_order_number():
    with connection.cursor() as cursor:
        cursor.execute("SELECT nextval('order_order_number_seq')")
        result = cursor.fetchone()
        return result[0]


class Order(ModelWithMetadata, ModelWithExternalReference):
    id = models.UUIDField(primary_key=True, editable=False, unique=True, default=uuid4)
    number = models.IntegerField(unique=True, default=get_order_number, editable=False)
    use_old_id = models.BooleanField(default=False)
    created_at = models.DateTimeField(default=now, editable=False)
    updated_at = models.DateTimeField(auto_now=True, editable=False, db_index=True)
…
    user = models.ForeignKey(
        "account.User",
        blank=True,
        null=True,
        related_name="orders",
        on_delete=models.SET_NULL,
    )
…
    channel = models.ForeignKey(
        Channel,
        related_name="orders",
        on_delete=models.PROTECT,
    )
…
        indexes = [
            *ModelWithMetadata.Meta.indexes,
            GinIndex(
                name="order_search_gin",
                # `opclasses` and `fields` should be the same length
                fields=["search_document"],
                opclasses=["gin_trgm_ops"],
            ),
            GinIndex(
                name="order_tsearch",
                fields=["search_vector"],
            ),
            GinIndex(
                name="order_email_search_gin",
                # `opclasses` and `fields` should be the same length
                fields=["user_email"],
                opclasses=["gin_trgm_ops"],
            ),
            models.Index(fields=["created_at"], name="idx_order_created_at"),
            GinIndex(fields=["voucher_code"], name="order_voucher_code_idx"),
            GinIndex(
                fields=["user_email", "user_id"],
                name="order_user_email_user_id_idx",
            ),
            BTreeIndex(fields=["checkout_token"], name="checkout_token_btree_idx"),
Warm-up
