Re: VIEWS compared to Nodes as Windows into data

Centuries ago, Nostradamus foresaw when "Dawn M. Wolthuis" <dwolt_at_tincat-group.com> would write:
> "Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message
> news:c6m06j$r1h$1_at_news.netins.net...
>> Given a database application implemented in an RDBMS with 632 tables where
>> we want to give Pat an online data catalog from which to shop for data
>> values by way of metadata, we would likely provide a set of SQL VIEWS,
>> correct?
>>
>> From what I have seen, if there is data in a supporting table XYZ that is
>> only sometimes needed when reporting about a particular entity (such as
>> Customers), then one might have two VIEWS of that data -- one with and one
>> without XYZ joined in.
>
> <snip>
> Is this an accurate perspective on SQL VIEWS? Are there "extra" VIEWS, more
> portals into the data, or whatever, created simply for performance reasons?
> Is there a DBMS that provides a better top level "data catalog" that doesn't
> include performance issues mixed with what data values you can "shop for"
> (query)?

VIEWS are created for all sorts of reasons, typically:

• To provide convenient perspectives on data;
• To structure the data better from a security perspective.

They aren't created for "performance" reasons; if anything, they are likely to cut performance slightly. Their point is either to provide better abstraction or to to hide details.

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