On Apr 24, 10:52 am, phancey <d..._at_2bytes.co.uk> wrote:
> If I only want to select 2 columns out of 5 for example, and those 2
> columns are the primary key on an IOT, is it possible or even
> worthwhile to index them separately from the IOT? The IOT would be a
> much wider index and therefore require more memory? If the 2 columns
> are likely to be in physical order anyway, wouldn't the normal index
> perform better?
>
> In SQL Server I have been able to create a clustered index and a
> normal index on the same 2 columns. The optimiser chooses the normal
> index when selecting just those 2 columns. But it seems Oracle won't
> let me define the same 2 columns(in the same order) twice.
>
> Phil
It is not worthwhile as the optimizer would automagically select the
index and the index only.
Why would the IOT be a much wider index?
Why would a 'normal' index perform better.
Why would you need to create 2 indexes on identical columns? If that
can be done in sqlserver, sqlserver is an even bigger piece of crap
than I already thought.
--
Sybrand Bakker
Senior Oracle DBA
Received on Tue Apr 24 2007 - 04:27:46 CDT
