You will need to set up a separate backup device for the FULL and the DIFF. When you create the Backup Device it is a single file. You can't save a FULL and a DIFF in the same Backup Device.
More information about backup devices can be found here: http://msdn.microsoft.com/en-us/library/ms179313.aspx
If you are trying to restore the database over an existing database and want to replace the data you will need to use the WITH REPLACE option in the restore. More information can be found here: http://msdn.microsoft.com/en-us/library/ms186858.aspx
REPLACE should be used rarely and only after careful consideration.
Restore normally prevents accidentally overwriting a database with a
different database. If the database specified in a RESTORE statement
already exists on the current server and the specified database family
GUID differs from the database family GUID recorded in the backup set,
the database is not restored. This is an important safeguard.
The REPLACE option overrides several important safety checks that
restore normally performs. The overridden checks are as follows:
Restoring over an existing database with a backup taken of another
database.
With the REPLACE option, restore allows you to overwrite an existing
database with whatever database is in the backup set, even if the
specified database name differs from the database name recorded in the
backup set. This can result in accidentally overwriting a database by
a different database.
Restoring over a database using the full or bulk-logged recovery model
where a tail-log backup has not been taken and the STOPAT option is
not used.
With the REPLACE option, you can lose committed work, because the log
written most recently has not been backed up.
Overwriting existing files.
For example, a mistake could allow overwriting files of the wrong
type, such as .xls files, or that are being used by another database
that is not online. Arbitrary data loss is possible if existing files
are overwritten, although the restored database is complete.
How Connection Pooling works
The issue with connection pool fragmentation is that each connection pool is bound to the exact text of the Connection String, including the SID of the Windows Login when using a Trusted Connection / Integrated Security. The connection pool works because the connection is exactly the same in every way.
Hence, changing the database after connecting doesn't change anything from a security perspective. The advice to change the database after connecting (which can also be done via the SqlConnection.ChangeDatabase
method), is to get around the fact that putting the "Initial Catalog" (or "Database") key/value pair into the Connection String means that those connections aren't using the exact same connection string.
With the above in mind, whether you are using Windows Logins (i.e. Trusted Connection / Integrated Security) or SQL Server Logins (specifying UserID & Password OR using a SqlCredential
),
if the web app connects as the same Login for all requests, then as long as you don't specify the database in the ConnectionString (or at least always specify the same database), and only change the database context after making the connection, then you will get the most re-use out of connection pooling since all connections will be able to use the same pool. Else you will get a pool per Database.
if the web app connects with different Logins, then:
- in the one-database-per-client model (assuming they are only allowed to connect to their database, hence using a different Login per client), you can either always specify the same database for that Login, or not specify any database in the ConnectionString and only change the database context after making the connection, and you will get a pool per Login (or per Database: they are kinda the same thing in this model).
- in the multi-tenant model (assuming the app makes calls to multiple databases), as long as you don't specify the database in the ConnectionString (or at least always specify the same database), and only change the database context after making the connection, then you will get a pool per Login. Of course, if you specify the database in the ConnectionString, then you will get a pool per Login per Database!
What this all means in practical terms
No, you cannot have a single connection pool and "prevent the user from making cross-database queries". The very nature of a connection pool it is that it is the same connection because the connection is not closed. You cannot differentiate permissions when there is nothing to differentiate; the same Login is still logged in, just issuing another command.
Reducing the number of connection pools down to a single pool is at odds with the desire to have different permissions:
If you want to prevent a Login from accessing more than their database, or maybe confined to their database and any "shared" databases, that requires different Logins, and each one will have their own pool. If you go with Contained Databases, you still need to specify either the UserId & Password OR the Initial Catalog in the Connection String, and hence the result will still be one connection pool per each variation.
If you want to have just one connection pool, then you have no choice but to always use the same security credentials (regardless of them being based in Windows or SQL Server). And the same credentials means the same permissions.
The bottom line is, the wording of that MSDN article is a bit confusing / awkward, and you are over-estimating their advice. The issue of Connection Pool Fragmentation really shows up when:
- you are changing both the security credentials AND the "Database" / "Initial Catalog" across connections
- the app is multi-tenant (i.e. not one database per customer) such that each Login can connect to multiple Databases.
Having multiple Logins that connect to multiple Databases will give you more pools that are less frequently reused. Given that the unused connections linger for "approximately 4-8 minutes" (taken from the MSDN page you linked to, the "Removing Connections" section), this creates the inefficient situation of having too many idle connections.
But, having one Connection Pool per-Login OR per-Database is actually just fine.
Please note, however, that even with one Connection Pool per-Login OR per-Database, you can still experience too many idle connections if you have a lot of clients (e.g. Web Apps, back-end processes, etc.) hitting SQL Server from different servers.
Best Answer
Maintenance Plans are actually SQL Server Integration Services packages stored in msdb.
You can see the binary package by looking at
msdb.dbo.sysssispackages
.You cannot easily modify the package using T-SQL, nor can you easily inspect the package contents to determine which databases are being backed up.
Instead of using Maintenance Plans, it is advisable to use SQL Server Agent in combination with some pre-designed set of scripts, such as those provided by Ola Hallengren or MinionWare