> 1. Outputting a top level JSON object without the additional column
> keys. IIUC, the top level keys are always the column names. A common use
> case would be a single json/jsonb column that is already formatted
> exactly as the user would like for output. Rather than enveloping it in
> an object with a dedicated key, it would be nice to be able to output it
> directly. This would allow non-object results to be outputted as well
> (e.g., lines of JSON arrays, numbers, or strings). Due to how JSON is
> structured, I think this would play nice with the JSON lines v.s. array
> concept.
>
> COPY (SELECT json_build_object('foo', x) AS i_am_ignored FROM
> generate_series(1, 3) x) TO STDOUT WITH (FORMAT JSON,
> SOME_OPTION_TO_NOT_ENVELOPE)
> {"foo":1}
> {"foo":2}
> {"foo":3}

Your example does not match what you describe, or do I misunderstand? I
thought your goal was to eliminate the repeated "foo" from each row...