Assuming the next snippet when creating a JSON column:

    from sqlalchemy.types import JSON as BaseJSON
    from sqlalchemy.dialects import postgresql


    JSON = BaseJSON()
    JSON = JSON.with_variant(postgresql.JSONB, 'postgresql')

I've noticed that the query did not work. Digging into the guts of py-mongosql I found this code:

def _is_column_json(col: MapperProperty) -> bool:
    """ Is the column a PostgreSql JSON column? """
    return isinstance(_get_column_type(col), (pg.JSON, pg.JSONB))

I was wondering if is not more correct to check against sqlalchemy.sql.sqltypes.JSON since it is the most generic type and base to the more specific posgresql variants. Is there any reason to keep it limited like it is?

I will make a PR with my suggested fix and a RFC.