public Reader getCharacterStream(String columnName) throws SQLException {
        return getCharacterStream(getColIdxByName(columnName));
    }
Retrieves the value stored in the designated column
of the current row as a <code>java.io.Reader</code> object.

<P><B>Note:</B> All the data in the returned stream must
be read prior to getting the value of any other column. The
next call to a <code>getXXX</code> method implicitly closes the stream.

@param columnName a <code>String</code> object giving the SQL name of
       a column in this <code>CachedRowSetImpl</code> object
@return a Java input stream that delivers the database column value
        as a stream of two-byte Unicode characters.  If the value is
        SQL <code>NULL</code>, the result is <code>null</code>.
@throws SQLException if (1) the given column name is not the name of
a column in this rowset, (2) the cursor is not on one of
this rowset's rows or its insert row, or (3) the designated
column does not store an SQL <code>CHAR, VARCHAR, <b>LONGVARCHAR</b>,
BINARY, VARYBINARY</code> or <code>LONGVARBINARY</code> value.
The bold SQL type designates the recommended return type.
src/main/java/org/replicadb/rowset/sun/rowset/CachedRowSetImpl.java