Syntax shorthand for updating only changed rows in UPSERT
There is no provision in SQL to say &quot;all columns except this one&quot;. (You can do something like that with jsonb or hstore.) Related answer with details:

Select columns inside json_agg

On second thought, you don't need this. You might as well update all columns. Postgres writes a new row version anyway, nothing lost.
INSERT INTO test_upsert AS t (some_id, a, b, note)  -- list is optional
VALUES ('c', 5, true, 'asdf')
ON     CONFLICT (some_id)
DO     UPDATE
SET    (some_id, a, b, note) = ROW (excluded.*)  -- ROW syntax
WHERE  (t.*) IS DISTINCT FROM (excluded.*)       -- again, compare whole row
RETURNING *;

You still have to spell out the column list once for the target list of SET. That's required. The rest can be shortened.
You might even omit the target list for the INSERT while targeting all columns anyway, but in most cases it's good form to spell it out, more robust against future changes.
The table alias is an optional additional syntax shorthand. Note that the AS key word is required for a table alias for the target of an INSERT - unlike most places for a table alias.

The manual on INSERT.

Or even shorter, yet:
...
WHERE  t IS DISTINCT FROM excluded
...

We can as well just use the table name (or alias) for the (well-known!) composite type. The only corner-case disadvantage of this: if there is also a column of the same name &quot;t&quot; (or &quot;excluded&quot;), it takes precedence due to Postgres syntax rules. (t.*) IS DISTINCT FROM (excluded.*) cannot be mistaken and is the slightly safer form. Related answer:

Convert a row to a nested JSON document containing all relations