Data order in journal and transanction pulls

I haven’t found confirmation one way or the other about the ordering of returned data when pulling these. From manual observation it seems that they are ordered by “transaction_id” in the case of transaction pulls and by “id” for journal pulls.

Is this something that can be relied upon? For example if I’m iterating through the returned data and instering it in to a database can I skip remaining entries as soon as I encounter an entry with a pre-existing value for the respective key?