Re: Posted Sunday 20th May 2007 07:50 GMT

The statement regarding the CBO is pointless without more information. If you are accessing more than quite a small percentage of data it IS actually MORE efficient to access it without the use of indexes, try it (if you haven't already) and see what happens with and without the index.

Even if you hint it to use an index and it is more performant for you at what cost is the performance increase? For example you may be annihilating disk IO. This might be fine in your case but is not necessarily good in every situation.

You may well have done all of this and found that actually the CBO really is choosing a bad plan - it's not unheard of, but your statement is a best misleading at worst plain wrong with out facts to back it up.