#[derive(sqlx::FromRow, Clone)]
pub(super) struct A<'a> {
  pub(super) content: Cow<'a, MaybeBig>, 
  ...
}

impl<DB, T> Type<DB> for Cow<'_, T>
where
  T: Type<DB>,
  DB: Database,
{
  fn type_info() -> DB::TypeInfo {
    T::type_info()
  }

  fn compatible(ty: &DB::TypeInfo) -> bool {
    T::compatible(ty)
  }
}

// Maybe this is unnecessary since smart pointers implement Deref for T
impl<'q, DB, T> Encode<'q, DB> for Cow<'q, T>
where
  T: Encode<'q, DB>,
  DB: Database,
{
 //  encode() omitted since it requires an additional ToOwned<Owned=T> bound on T 

  fn encode_by_ref(&self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull {
    T::encode_by_ref(self, buf)
  }

  fn produces(&self) -> Option<DB::TypeInfo> {
    T::produces(self)
  }

  fn size_hint(&self) -> usize {
    T::size_hint(self)
  }
}

impl<'r, DB, T> Decode<'r, DB> for Cow<'static, T>
where
  T: Decode<'r, DB> + ToOwned<Owned = T>,
  DB: Database,
{
  fn decode(value: <DB as HasValueRef<'r>>::ValueRef) -> Result<Self, BoxDynError> {
    T::decode(value).map(|t| t.to_owned()).map(Cow::Owned)
  }
}