There are three restrictions on indexing and partitioning: a unique index cannot be local non-prefixed; a global non-prefixed index is not possible; a bitmap index cannot be global. Why these limitations? I suspect that they are there to prevent us from doing something idiotic.
I see posts on Oracle related forums about various releases (anything that isn't 11.x or 12.x) being "unsupported". This is wrong. Of course you should upgrade any 9i or 10g databases, but you don't have to.
Matthew Morris (who makes many constructive and knowledgeable contributions to the forum) has written a series of study guides for the OCA/OCP exams. I asked him if I could have a copy of one to review. The result: it's very good. This is a copy of the review I put up on Amazon.
The other day, I was asked how to move a table from one schema to another. The answer, as we all know, is "you can't do that: you have to create a new table as a copy of the old one, or use export/import. It will take a long long time." Not true.