RE: Views vs. Direct SQL - Overhead Savings?

I look at views as a way of allowing access to certain columns of a
table and not others. If I lock a table so one cannot access it
directly but make limited views for certain access, then I have created
column level security, sort of.
For instance, create a view that only shows the last 4 digits of a
credit card or SSN, masking or hiding the rest of the number.



Chris Bipes
Director of Information Services
CrossCheck, Inc.

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Vern Hamberg
Sent: Wednesday, September 02, 2009 2:39 PM
To: Midrange Systems Technical Discussion
Subject: Re: Views vs. Direct SQL - Overhead Savings?

To add to the other remarks - a view is not like a traditional logical
file, in that there is really not an access PATH stored there. It
basically encapsulates a SELECT statement, and that statement will be
executed afresh each time the view is used. As Birgitta suggests, there
might be an access PLAN associated with the view. And those can now be
cached, for improved performance. Of course, if the environment or
number of records changes or whatever, then all bets are off - the
engine has to run optimization again.

Now there ARE improvements, as others have said. I worked with Elvis
some years ago, and we often saw nested views being very slow. I'm glad
that seems to be fixed.