问题
What is the difference of the sys.master_files and sys.database_files? I have about 20 databases in my instance but when I query the sys.master_files I do not receive any rows. Why? When I query sys.database_files I get the information about the database files concerning the current database.
回答1:
sys.master_files :
Contains a row per file of a database as stored in the master database. This is a single, system-wide view.
sys.database_files :
Contains a row per file of a database as stored in the database itself. This is a per-database view.
So, SELECT * FROM sys.master_files should list the files for each database in the instance whereas SELECT * FROM sys.database_files should list the files for the specific database context.
Testing this here (SQL 2K8), it works as per the above?
Update: If you're not seeing rows from sys.master_files, it could be a permissions issue as BOL states:
The minimum permissions that are required to see the corresponding row are CREATE DATABASE, ALTER ANY DATABASE, or VIEW ANY DEFINITION.
Whereas for sys.database_files just requires membership in the public role.
来源：https://stackoverflow.com/questions/4174520/sql-server-sys-master-files-vs-sys-database-files