`UPDATE FROM` syntax to allow updates based on result set

OrientDB Version: 3.1.10 (docker)

There doesn't seem to be a way to pass a result set to an UPDATE command, at least not from a subquery or a variable. The same applies for CREATE VERTEX. INSERT, however, does support this feature with the FROM keyword.

Practical impact: creating a batch script to handle updates from input records to output records seems to only be possible by using UPDATE Output SET ... to define each and every field.

So, for example, this does NOT work:

LET $inputItems = (SELECT FROM Input);
FOREACH ($inputItem in $inputItems) {
  UPDATE Output FROM $inputItem WHERE id = $inputItem.id;
}

Question: Is there a syntax to do this that works with UPDATE? CREATE VERTEX can be worked around using INSERT, but that doesn't work when updating existing records.

These kinda make sense as syntaxes, but don't work, either:

CREATE VERTEX Output CONTENT $inputItem;
CREATE VERTEX Output CONTENT $inputItem.toJSON();
CREATE VERTEX Output CONTENT (SELECT FROM Input);

Just like other parse errors, these produce a a misleading error about whatever expression is first in the block in which the error occurs.

Reproduce the UPDATE and CREATE VERTEX examples against OrientDB 3.1.10 in Docker, then trace how UPDATE, INSERT, and subquery result sets are parsed and executed. Done means UPDATE can consume a result set or variable as requested, with parse errors reporting the actual syntax problem.