Database Snapshots - clarification quesetion

[Ovatvvon]

Hi Everyone,

According to:

http://msdn.microsoft.com/en-us/library/ms187054.aspx

Database Snapshots in SQL 2005 do not provide a "true" separate database to read from, for reporting purposes. Instead, only initial updates at the page level will be stored in the snapshot, but the user will be referred to the source database for any data that has not been updated since the snapshot was taken.

However, at the bottom of that MSDN page, it reads as such:

"The only exceptions are when the source database uses full-text search or database mirroring, which disable themselves on a snapshot by altering some values in the snapshot's metadata."

Does anyone know precisely what that means? Does that mean that if you setup database mirroring and then setup a snapshot on the mirror, that all data will reside in the snapshot itself, and the user will not be referred to the source database? Or am I reading that wrong?



-Ovatvvon :-Q

 

[MDXer]

I believe it is the opposite that even though you referenced the snapshot you would be passed through to the database.

 

[Ovatvvon]

I checked with DBA's for another client who used this solution. Apparently the deal is, if you have a database snapshot on the same server as the source database, it will forward the request through to the source database, except on those rows that have been changed, in which case it will ref the snapshot.

For the case where a database is mirrored to another server, the mirror cannot be accessed, so you have to setup a database snapshot on that mirror. when accessing the snapshot, it will forward to the mirror, and for whatever reason, it will work there, except on records that are changed, in which case you will still reference the snapshot. But it sounds like it does not actually forward the request back to the orig. source database on the other server.

Can anyone verify whether this is accurate, or that what MDXer said was correct?



-Ovatvvon :-Q