Copy blob portion to another blob

Hi,

I am using dbms_lob.copy to copy the portion of one blob to another. It works correctly, but what surprises me is the fact that this copy works about 5 times slower than loading blob data from the server to the client, triming it on the client and uploading it back to the server! It should have been faster because dbms_lob.copy [being executed in a stored procedure at the server side] shouldn't cause any network traffic at all! Is there another faster method to copy a portion of a blob to another?

A side question. When exactly createtemporary procedure (the one to create temporary blobs) was introduced? I've noticed that it is missed on Oracle 8.05 but there on 8.1.x. Is there an alternative to this procedure when it is not available?

-- 
Mike Kluev.

PS. Remove "-delete-." part of my e-mail address to reply.