Currently, JSON_TABLE doesn't allow one to extract a JSON "subdocument" into a JSON column.
Both the SQL Standard and MySQL-8 provide this capability. This task is about implementing it.
I was sent a patch with MySQL-8 syntax support, so I assume we're going to implement MySQL-8 compatible syntax, which is just to allow specifying column type as JSON. For example:
should emit [1,2,3,4].