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System database
One of the basic skills of a database administrator (DBA) is a deep understanding of the system database SQL database engine. SQLSERVER database developers understand the system comes with a database is also very useful. Here are some of the system database of them. (Note: If you decide to look at these systems, databases, then you need to have a development database.)
Master
Master database stored on the database on all entities SQLSERVER, it is the engine fixed up the adhesive. If you do not use the master database, SQLSERVER will not start, so you have to carefully manage the database. It is necessary to make regular backups of the database. We recommend backing up the master database when the database is changed.
This database includes information such as the system log, configuration settings, etc. connected SERVER, as well as for other general information of the database system and user entity. There is also the primary database extended stored procedure, it is possible to access external processes, so that you can interact with the characteristics of the disk subsystem and system API calls and so on. These processes are generally used as such a modern C ++ programming language.
If, unfortunately, encountered a system crash and recovery must be the primary database, you can see MCSE / MCDBA StevenWarren published on TechRepublic article. This article speaks very thorough, it explains some special steps to restore this important database needs.
Model
Model is used to create a new database on the user entity template database . You can put any stored procedures, views, users, etc. in the model database, so that when you create a new database, the new database will contain all of the objects in your model of the database. Therefore, the new database should have a minimum as large as the model database. We will specify when creating the database size of the database, usually greater than the size of the model database, it is because it fills an empty page.
Tempdb
As its name suggests, tempdb there temporary objects, such as global and local temporary tables and stored procedures. This database SQLSERVER every restart time will be re-created, and the object is an object that contains the definition of the model based on the database to be created. In addition to these objects, tempdb there is also other objects, such as tables variable, the result set from the table valued function, and the provisional table variables. Because tempdb will retain these object types for all databases on SQLSERVER entity, so the database to optimize the configuration is very important.
In SQL Server 2005 in, tempdb database as well as an additional task; it is used as a repository of some of the features, such as the new snapshot isolation layer and the online index operations. A brief description of the new isolation layer, please refer to my article on the SQLServer 2005's advanced features.
Distribution
When your SQLSERVER entity is configured to replicate distribution SERVER, this database will be added to your system. By default, the name of the database is the distribution, but you can change its name. This database is used to save the history and snapshots, merge and transactional replication metadata.
Msdb
Msdb database used to store the database backup, SQL Agent information, DTS packages, SQLSERVER tasks and other information, such as log shipping and replication of such information.