maximum field lengths

[eluser]Unknown[/eluser]
I wish to grab the maximum _allowable_ field length for a mysql field.
NOT the value returned by field meta data which only returns the length of the values in the field.
The value would normally be returned by msyql_field_len that provides the maximum allowable length as described by the database schema.
the value returned by field meta data with CI is just a string length of the longest value in that column.

Is this possible with CI?

Kind regards
Kevin