>>One of the easier cases would be non-overlapping (exclusive) constraints
>>on union subtables on the joined column.
>>
>>This could serve as a "partition key", or in case of many nonoverlapping
>>columns (ex.: table is partitioned by date and region), as many
>>partition keys.
>
>
> Yes, thats my planned direction.
In case you didn't know btw, MySQL 5.1 is out with rather extensive
table partition support. So get coding :D
Chris