Datafusion doesn't support JSON or VARIANT types yet; however this crate can be used to add support for SQL queries that parse and query JSON-formatted strings on the fly, e.g:

SELECT *
FROM my_table
WHERE json_get_bool(json_column, 'my_bool_field') = true
  AND json_get_int(json_column, 'complex_field', 5, 'int_field') = 0;

This will work well with our current VARIANT encoding as arrow Utf8 strings.