May 5, 2010 at 2:09 pm
Many articles says that the Database Mirroring (with snapshot backup) is as good as replication.
So I want to see this for myself and I don't think so.
I am using sql server 2005. I setup the Database Mirroring and created a snapshot backup of the database mirroring since the database mirroring is not accessible.
when there is a change on the Principal partner, the Mirrored Partner gets the change.
However, the snapshot Database backup did not reflect the changes afterwards unless we re-create the snapshot backup, but then the user of the database snapshot gets disconnected.
If the snapshot is getting re-created and the user is in the middle of a transaction using the snapshot database, it will get knocked out. In Replication, the user never gets disconnected.
So I don't see how this is compatible to transaction Replication.
May 5, 2010 at 2:13 pm
A database snapshot is a point in time picture of the data. If you take a snapshot at 8:00 AM, you wont see any changes to the data that are made after 8:00 AM.
May 6, 2010 at 7:03 am
I think that the articles you are reading are missing the point a bit. At best, snapshot replication might be similar to mirroring plus a database snapshot.
Mirroring definitely does not give you any (near) real time access and it is not designed to do that.
As you have found, transactional replication does give you near real time access to data from a separate database. You could consider that database mirroring does apply all transactions from the source database to the mirror database. However, unless you are continuously re-creating snapshots, there is no way to get access to the data.
I suspect that the articles about mirroring must be using transactional replication as a metaphor for how the transactions get from the source database to the mirror but are not intending to imply that the data is accessible.
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