SQL Server Backup and Restore - Simple Talk

Chapter 9: File and Filegroup Backup and Restore
IF NOT EXISTS ( SELECT name
FROM sys.filegroups
WHERE is_default = 1
AND name = N'Secondary' )
ALTER DATABASE [FileBackupsTest] MODIFY FILEGROUP [Secondary] DEFAULT
GO
Listing 9-3: A template for creating a multi-filegroup database.
Crucially, we can now dictate, to a greater or less degree, what data gets put in which
filegroup. In this example, immediately after creating the database, we have stipulated
the SECONDARY filegroup, rather than the PRIMARY filegroup, as the default filegroup for
this database. This means that our PRIMARY filegroup will hold only our system objects
and data (plus pointers to the secondary data files). By default, any user objects and data
will now be inserted into one of the data files in the SECONDARY filegroup, unless this was
overridden by specifying a different target filegroup when the object was created. Again,
the fact that we have multiple data files means that we can back each file up separately, if
the entire database can't be backed up in the allotted nightly window.
There are many different ways in which filegroups can be used to dictate, at the file level,
where certain objects and data are stored. In this example, we've simply decided that the
PRIMARY is for system data, and SECONDARY is for user data, but we can take this further.
We might decide to store system data in PRIMARY, plus any other data necessary for the
functioning of a customer-facing sales website. The actual sales and order data might be
in a separate, dedicated filegroup. This architecture might be especially beneficial when
running an Enterprise Edition SQL Server, where we can perform online piecemeal
restores. In this case, we could restore the PRIMARY first, and get the database back
online and the website back up. Meanwhile we can get to work restoring the other,
secondary filegroups.
We might also split tables logically into different filegroups, for example:
• separating rarely-used archive data from current data (e.g. current year's sales data in
one filegroup, archive data in others)
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