Re: Using views inside a View

On Tue, 22 Feb 2005 10:19:52 +0100, Frank van Bortel wrote:

>>
>> Back to this one - would it be fair to provide the following ROT to the
>> OP's question:
>>
>> "The technical issues that caused performance concerns related to nested
>> views in [very old] versions of Oracle are, for the largest part, no
>> longer relevant.
>>
>> However, inappropriate use of views can have side effects such as
>> unacceptable performance and resource issues. These side effects, such as
>> unnecessary aggregation within views, could become significant in ad-hoc
>> environments.
>>
>> Suitable documentation for views as well as proper analysis, including
>> explain plans, should be considered for all 'permanent' SQL statements."
>>
>> FGB

> 
> I like that - it may just be a little long for a ROT.
> The part that sticks will probably be just the first
> sentence, which is OK by me for a ROT.

You're right - I tend to be wordy. Let's try this on for size:

"Careless (or novice) use of nested views can have issues because of side effects of unseen operations such as aggregations.

Careful use of relevant and documented views should not (normally) have performance impacts.

Make sure you test."

FGB Received on Tue Feb 22 2005 - 06:09:53 CST