Definition of BCV

Could someone explain to me what the acroymn BCV means and how it is applied with an SQL database?
ThanksYou probably mean BCP, the Bulk Copy Program provided as a SQL Server utility with the SQL client tools.

You might actually mean BCV if you are using EMC storage, in that context it means Business Continuation Volume.

-PatP|||Thanks Pat for the response ... I did mean Business Continuation Volume because our client is using EMC storage. Can you explain to me what this actually is and how it is benefical as a tool to use?|||http://www.emc.com/products/product_pdfs/pdg/timefinder_pdg.pdf?emccomjsessionid=23057310987216 72334|||Actually, EMC does a better job explaining (http://www.emc.com/pdf/business_centers/windows/Microsoft_SQL.pdf) how to use BCVs with SQL Server than I can. We've never gotten them to work to my satisfaction.

The basic idea is that a BCV will allow you to mirror data in real time. In SQL 7.0 hooks were added, which were refined in SQL-2000 to allow an application to "freeze" a disk volume. This freeze would effectively flush the disk buffers to disk as of a specific point in time, almost as though the database had been stopped (to detach it). The theory is that you could mirror a BCV volume to a production volume, freeze the SQL files, break the mirror, then "thaw" the SQL files again, all without the end user knowing or caring that anything had ever happened.

Anywho, see the EMC document for a better description. While I love EMC in general, we (my firm working with EMC) were never able to make BCVs work in production.

-PatP

Defaults

1) Defaults are applied before transactions.
Defaults incur more overhead than constraints but less than triggers.
Defaults are less functional than constraints or triggers.
2) Defaults are applied after transactions.
Defaults incur more overhead than constraints but less than triggers.
Defaults are less functional than constraints or triggers.
3) Defaults are applied before transactions.
Defaults incur more overhead than constraints but less than triggers.
Defaults are more functional than constraints but less than triggers.
4) Defaults are applied after transactions.
Defaults incur less overhead than constraints or triggers.
Defaults are more functional than constraints but less than triggers.
5)5)Defaults are applied before transactions.
Defaults can only be applied to one column per row.
Defaults are less functional than constraints or triggers.
I go with option number 4. All are agree with me ?
Thanks
JOHN
No - but the statements are poorly worded. Comparing the functionality of
defaults and constraints is inappropriate (even though MS has lumped them
together - a default is a type of constraint) since they have different
purposes. IMO, a default is less "functional" than a constraint.
Certainly, both are less functional than triggers. The terminology "before
transactions" and "after transactions" is meaningless. If I had to guess, I
would choose "before transactions" simply because the default is applied
before the insert statement completes.
I would choose 5 but the middle statement can be interpreted in different
ways. The part about "per row" is especially confusing (perhaps
intentionally) - defaults (and constraints and triggers) are never defined
at the row-level. A default is associated with a single column, but each
column can have a default.
"John" <naissani@.hotmail.com> wrote in message
news:OU4$buBIFHA.608@.TK2MSFTNGP10.phx.gbl...
> 1) Defaults are applied before transactions.
> Defaults incur more overhead than constraints but less than
triggers.
> Defaults are less functional than constraints or triggers.
> 2) Defaults are applied after transactions.
> Defaults incur more overhead than constraints but less than
triggers.
> Defaults are less functional than constraints or triggers.
> 3) Defaults are applied before transactions.
> Defaults incur more overhead than constraints but less than
triggers.
> Defaults are more functional than constraints but less than
triggers.
> 4) Defaults are applied after transactions.
> Defaults incur less overhead than constraints or triggers.
> Defaults are more functional than constraints but less than
triggers.
> 5)5)Defaults are applied before transactions.
> Defaults can only be applied to one column per row.
> Defaults are less functional than constraints or triggers.
>
>
> I go with option number 4. All are agree with me ?
>
> Thanks
> JOHN
>
>
|||On Thu, 3 Mar 2005 13:05:30 -0500, John wrote:

> I go with option number 4. All are agree with me ?
Hi John,
I don't.
Defaults are applied, neither before or after transactions, but as part
of a transaction. Anything that is applied before or after a transaction
would not be affected by a rollback of that transaction. If I ever see a
case where the insert statement is rolled back but the default values
used in that statement persist in the database, I'll be on the phone
yelling "BUG" in MSPSS' ears before you can say "Rollback".
Defaults incur less overhead than triggers. I have never compared the
overhead of defaults to that of constraints, since this would be a
meaningless comparison. I can't replace either one with the other, they
yield different functionality. It would be about as meaningless as
comparing the costs of your car with that of your microwave oven.
You could call defaults less functional than triggers, but in the same
sense as calling a chair less functional than a pile of wood, a supply
of nails, a saw, and a hammer. You can make anything you want from the
wood, including a chair, but it takes much work. If you just want to sit
down for a while, using the chair is by far the better option.
Best, Hugo
(Remove _NO_ and _SPAM_ to get my e-mail address)