Rick,
Scott was one of my students, and he was working on DERBY-396. He has since
graduated and moved on from our university. He ran into some problems with DERBY-396,
which can simply be summed up as problems with return values. When you are accessing a
table to alter it, you need to lock the table in order to keep other users from altering
the table at the same time. Once the change has been made, you can then release the lock
on the table, which is essentially a "return". This isn't a problem when you
are adding columns, as there is nothing to return. But the existing circumstance for
RENAME and DROP require that the object being renamed or dropped is returned. This
results in a case where you have a return within a return - something that doesn't work
so well with Java. He tried several different ways to work around this problem, including
not returning the objects when performing RENAMEs and DROPs, returning only the node but
not the lock, and casting the node to be renamed o
r
dropped as the same object type as the return type. He also tried calling separate rename or drop methods, but the object being returned was not the same type as the object type returned by the alter table commands.
The result on his final report was "Due to time constraints and the problems
of requiring rename and drop statements to return values inside the alter table method, I
was not able to implement the rename and drop column functionality."
I had suggested to Scott that he release working on the feature once he
had graduated until he was able to begin working on the project again on his
own time. I guess that he didn't get around to doing that. :(
I have a hard copy of his final report, but I can try to relay any
information from it to whoever would like to know.
darcy
Hi Scott,
Please forgive me for putting you on the spot by paging you in the subject line
of this message. I
have tried to privately ping your JIRA email address ([EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>), but the mail bounced back.
You graciously volunteered to work on DERBY-396. The community wants to know
whether you'll be
able to check in some of your code for the upcoming 10.2 release. Please feel
free to ask the
community for advice. Many people are keen to see this feature and would be
delighted to help out
any way they can.
Thanks,
-Rick
--
Dr. Darcy Benoit
http://cs.acadiau.ca/~dbenoit/
