created_at vs meaningful db column name , or both?
If you're setting a standard that all tables need a column_x, then the standard columns need to be... well... standard. The only way for the columns to be generalisable sensibly in the way you describe is to have created_at be metadata about the record and not the data for the row. processed_at is a different, separate data point that says something about the external world. If you hijack the created_at because it has a reasonably similar name then you've de-standardised the usage of that column - at which point why bother adhering to the standard rigorously? Just name each column what it is.


  TL;DR: use both if you need the standard columns to support your ORM. Don't hijack created_at for non-metadata