As I detailed elsewhere, the problem with this assumption is that you are one-off optimizing by encoding metadata about the data in the query. So while this spe

As I detailed elsewhere, the problem with this assumption is that you are one-off optimizing by encoding metadata about the data in the query. So while this specific query has been made more optimal, the underlying problem with the database remains, and thus you will invariably face and then have to work around the same problem numerous times. Or more often one won't because the legacy of hundreds of slow but not terrible queries accumulate. It becomes a death by a thousand cuts, which is the end result of many heavily used databases. My example in SQL Server sees the simple addition of a single distinct index to give that same metadata to the query planner, yielding the identical plan for the first and last. And this same benefit will flow to every query that follows the same path.