Why won't Oracle alter the size of a column that is used for sub partitioning?

Question

I am trying to resize a varchar2 column, when I get an ORA-14265 error:

ORA-14265: data type or length of a table subpartitioning column may not be changed

With Oracle providing the unhelpful:

// *Cause: User issued ALTER TABLE statement attempting to modify // data type and/or length of a column used to subpartition the // table named in ALTER TABLE statement, which is illegal

// *Action: Avoid modifying data type and/or length of table // subpartitioning column(s)

So I get that Oracle doesn't want me to alter the column. I presume the hash used for the subpartition would be broken by this. How do I get around this though?

The only suggestion I have found so far that seems plausible is to rename the existing table, and recreate the original with updated schema, then select the data from into the recreated table.

I don't particularly like this idea, for reasons of effort and likelihood of human error:

• We have lots of partitions, and behind the scenes I'd have to manually ensure the new table matched up identically, so that supporting maintenance scripts could continue along nicely.
• Then there is disk space. We keep 9 rolling months of data, and I don't have room to suddenly double up on this one table.

Any suggestions would be much appreciated. I hope I'm just missing something easy. Also, if anyone wants to let me know why oracle can't rearrange the data on disk and create a new subpartition hash automagically that would be great.