Database Files Doubt

[Former Member]

Hello All,

SQL Server 2005 databases have types of files:

Primary data files

The primary data file is the starting point of the database and points to

the other files in the database. Every database has one primary data file.

The recommended file name extension for primary data files is .mdf.

Secondary data files

Secondary data files comprise all of the data files other than the primary

data file. Some databases may not have any secondary data files, while others

have multiple secondary data files. The recommended file name extension for

secondary data files is .ndf.

But when I am checking the Database properties of SQL server Management Studioof our BI System,But one doubt I am having if the DATA2 & DATA3 files are secondary & with the extension ndf then why it is showing PRIMARY in the Filegroup??For DATA1 Files it should be primary but why for others it is also showing Primary even the the extension is ndf??

[Former Member · Accepted solution]

Hi,

please have a look at [this|http://msdn.microsoft.com/en-us/library/ms179316%28SQL.90%29.aspx] article. With filegroups you can group your database objects (files, tables, indexes). Let me quote one sentence:

The primary filegroup contains the primary data file and any other files not specifically assigned to another filegroup.

SAP only uses the primary filegroup, thats why all your datafiles are assigned to it.

Sven