public override int Size()
{
/*
* If stuff was removed from the index during this tx and during the same tx a query that matches them is
* issued, then it is possible to get negative size from the IndexHits result, if exclude is larger than source.
* To avoid such weirdness, we return at least 0. Note that the iterator will return no results, as it should.
*/
return(Math.Max(0, _source.size() - _removedInTransactionState.Count));
}