If we want to enable a seamless transition for saved queries, we need to support mixed-type comparisons. Saved queries are likely to have clauses like | WHERE ts > "2023-10-23T13:00:00Z", and the auto-casting will promote the string to a millisecond date and the timestamp to a nanosecond date. For that to then work, we need to support a comparison between millisecond dates and nanosecond dates.