Re: maximum for auto_explain.log_min_duration doesn't seem to make sense

​I suspect that the counter to which that value is being compared also wants to be an INT and if one checks for "val > INT_MAX" then val cannot be restricted to an integer (and since we are capturing time we need some unknown buffer).

As for the post question: What can I do if I want to log even longer-running queries on a data warehouse?

The answer is "nothing special, anything running longer than the supplied value will be logged".  What you cannot do is choose not to log a subset of queries that take longer INT_MAX/1,000 and less then infinity - once you hit INT_MAX/1,000 you must log it.

David J.