@RickJames what SQL? I've included all the queries apart from the list of selected columns.

Just to get me moving on this, I'm going to attempt to switch this to SELECT ... FROM Account acc LEFT JOIN Address addr ON acc.id = addr.account_id

It's nicer to have a solution that works globally in a query - for example the above won't work for my charset of utf8mb3

There is however a an answer here: stackoverflow.com/questions/21829957/… the order appeary to mostly depend on the index used, although I've also seen that it is ordered by disk order which would be harder to predict.

None of these answers actually answer the question. Yes I know that the order COULD be anything, it COULD change - but what IS it - it will be definable somehow, even if that definition is random by nature of multi-threading race conditions. This is the answer I want because I have existing code that doesn't specify order and I want to know what it does currently.

Just for clarity, by "external" I mean separately from the rest of the record as described here dev.mysql.com/blog-archive/externally-stored-fields-in-innod‌​b

I think you may have misunderstood what I mean by "stored externally" - I mean the feature of MySQL where it will store a BLOB outside of the normal table storage but inside the database.

I am doing so but that takes time.