partitioning by highly skewed data

[Hiroshi Takenaka]

Will it be possible to partition one specific partiton further?

For example, we have a 1TB table. We want to partition it,
and spread over 10 * 140GB disks using one column.
But, unfortunately, 20% of records have NULL on that column.

It would be nice, if we can partiton those records further
by using another column or some random value.
I think it should be easy if user can define and use
a custom partitioning function.

Regards
Hiroshi