Context Navigation

Changes between Initial Version and Version 1 of Ticket #36875, comment 3

initial	v1
4	4
5	5	This is particularly relevant as the ORM doesn't do a good job at differentiaing nullable expression, we can't use `expr.output_field.null` as we don't update this flag transitively when performing outer joins. That's the main reason why we systematically `Coalesce` each expression.
	6
	7	Implementing a reliable `Expression.is_nullable` property is not an easy task so we'd need a better rationale than the provided generated SQL readability concerns to accept this ticket IMO.