If a column’s value is unchanged by an UPDATE is the KV record still written and is it still replicated or does nothing happen?
If the value is unchanged because it was excluded by a WHERE clause on the UPDATE, then there will be no record written in KV.
If the value is unchanged because the result of executing the SET happens to produce the same value that was there before, then the record is still overwritten in KV.
Also we try to only update the columns effectively modified by the UPDATE.
Does this answer your question?
Yes, this does, thank you!