Re: Need Help on Views

Hi folks,

I don't have many performance problems with views. But try to avoid a view build on several layers of views.
Ex: View1 has "From view2"; View2 has "from view3", etc. This tends to confuse the optimizer, and the query plan may not be the best. Also, avoid creating a view with an outer join to another view. That will also affect performance.

Sylvain Leclerc
sleclerc_at_magrit.com

> -----Original Message-----
> From: peter.schneider_at_okay.net (Peter Schneider)
> [SMTP:peter.schneider_at_okay.net]
> Posted At: Thursday, May 07, 1998 9:17 PM
> Posted To: server
> Conversation: Need Help on Views
> Subject: Re: Need Help on Views
>
> On Thu, 7 May 1998 16:49:58 +0300, "Andrew Protasov"
> <protasov_at_percombank.kiev.ua> wrote:
>
> >Hi Scott,
> >
> >My point of view is you should use views where is it possible. They
> don't
> >damage performance in any way. They provide additional security level
> >and additional independence level between your application and data.
> >Your application should always use SQL statements like
> >select * from <view name>
> >or
> >select * from <view name> where <some condition>
> >where condition is generated dynamically in application.
> >You can always change view definition without changing client side
> code
> >using this approach. This is very flexible.
> >
> > Andrew Protasov
> >
> >Scott Fletcher wrote in message
> <35505803.0_at_newsprime.tidalwave.net>...
> >>
>
> [when and when not to use views...]
>
>
> Hi Andrew,
>
>
> I agree with your point about having an additional abstraction layer
> between your code and your data, but there's one aspect that one must
> keep in mind when designing views:
>
> If you're using Des2K with the generators (R1.x) , you'll have the
> requirement that the frontend must be able to issue direct DML against
> your data, so you must either have only updateable views, or must code
> the DML yourself by some kind of PL/SQL API to your tables. So you'll
> end up not using Des2K to the fullest extent of productivity that's
> possible when you do not have this abstraction layer.
>
> BTW, does anyone know whether Des2K R2 is released already ? From what
> I know, R2 will allow more flexibility and provide more design options
> for such issues than 1.x does.
>
>
> Regards,
> Peter
>
>
> --
> Peter Schneider
> peter.schneider_at_okay.net
Received on Fri May 08 1998 - 08:52:49 CDT