Page Checksums?

Hello,

Does SQL have any sort of checksum value attached to each 8K page or is
there a feature we can turn on to enable such a checksum?  I'm trying to
optimize our block data synchronization product specifically for SQL
databases.  Our product is similar in technology to rsync.  We currently use
MD5 checksums which can be resource intensive, but are very accurate.  We
are hoping that SQL already performed some checksum for each 8K page we
could utilize to compare at a page level rather than generating our own MD5
checksums.  Please let me know if SQL has such a technology or if you
have any suggestions.

Thank you,
David Aschmann

This feature is in SQL Server 2005.

--
--
Wei Xiao [MSFT]
SQL Server Storage Engine Development
http://weblogs.asp.net/weix

This posting is provided "AS IS" with no warranties, and confers no rights.

"DavidMA" <davidlisaa-news@yahoo.com> wrote in message
news:8E38FA65-DEFC-48A5-B89D- A27E4693BDC4@microso
ft.com...
> Hello,
>
> Does SQL have any sort of checksum value attached to each 8K page or is
> there a feature we can turn on to enable such a checksum?  I'm trying to
> optimize our block data synchronization product specifically for SQL
> databases.  Our product is similar in technology to rsync.  We currently
> use
> MD5 checksums which can be resource intensive, but are very accurate.  We
> are hoping that SQL already performed some checksum for each 8K page we
> could utilize to compare at a page level rather than generating our own
> MD5
> checksums.  Please let me know if SQL has such a technology or if you
> have any suggestions.
>
> Thank you,
> David Aschmann

The only thing SQL Server has is torn page detection, which basically flips 
a set of bits (spread
around the page) all to 1 or 0. When read, all should be 1 or 0, or you have
 a torn page. You can
turn this off at the database level. As already noted, checksum will come in
 2005.

--
Tibor Karaszi, SQL Server MVP
http://www.karaszi.com/sqlserver/default.asp
http://www. solidqualitylearning
.com/


"DavidMA" <davidlisaa-news@yahoo.com> wrote in message
news:8E38FA65-DEFC-48A5-B89D- A27E4693BDC4@microso
ft.com...
> Hello,
>
> Does SQL have any sort of checksum value attached to each 8K page or is
> there a feature we can turn on to enable such a checksum?  I'm trying to
> optimize our block data synchronization product specifically for SQL
> databases.  Our product is similar in technology to rsync.  We currently u
se
> MD5 checksums which can be resource intensive, but are very accurate.  We
> are hoping that SQL already performed some checksum for each 8K page we
> could utilize to compare at a page level rather than generating our own MD
5
> checksums.  Please let me know if SQL has such a technology or if you
> have any suggestions.
>
> Thank you,
> David Aschmann

Wei,

You do know the page header offset, and length, for the checksum value?
Thank you!

"Wei Xiao [MSFT]" wrote:

> This feature is in SQL Server 2005.
>
> --
> --
> Wei Xiao [MSFT]
> SQL Server Storage Engine Development
> http://weblogs.asp.net/weix
>
> This posting is provided "AS IS" with no warranties, and confers no rights
.
>
> "DavidMA" <davidlisaa-news@yahoo.com> wrote in message
> news:8E38FA65-DEFC-48A5-B89D- A27E4693BDC4@microso
ft.com... 
>
>
>

I do not know if dbcc Page works for YUKON, but if it does, you could use
dbcc Page to see the page and it should show the header field names as
well..

--
Wayne Snyder, MCDBA, SQL Server MVP
Mariner, Charlotte, NC
www.mariner-usa.com
(Please respond only to the newsgroups.)

I support the Professional Association of SQL Server (PASS) and it's
community of SQL Server professionals.
www.sqlpass.org

"Tibor Karaszi" <tibor_please.no. email_karaszi@hotmai
l.nomail.com> wrote in
message news:uKjWAdoYFHA.3572@TK2MSFTNGP12.phx.gbl...
> The only thing SQL Server has is torn page detection, which basically
> flips a set of bits (spread around the page) all to 1 or 0. When read, all
> should be 1 or 0, or you have a torn page. You can turn this off at the
> database level. As already noted, checksum will come in 2005.
>
> --
> Tibor Karaszi, SQL Server MVP
> http://www.karaszi.com/sqlserver/default.asp
> http://www. solidqualitylearning
.com/
>
>
> "DavidMA" <davidlisaa-news@yahoo.com> wrote in message
> news:8E38FA65-DEFC-48A5-B89D- A27E4693BDC4@microso
ft.com... 
>
>