Chapter 3 PHYSICAL DATABASE DESIGN AND IMPLEMENTATION 111
Chapter 3 PHYSICAL DATABASE DESIGN AND IMPLEMENTATION 111 covers the exam objectives for the physical database design section of the Database Development SQL Server 2000 exam, including the hardware, the operating system, SQL Server, the database, all database objects, and the application. Many of these features are overviewed in this chapter but are further defined in other chapters throughout the blog. CREATING AND ALTERING DATABASES . Create and alter databases. Considerations include file groups, file placement, growth strategy, and space requirements. The file format in SQL Server 2000 has not significantly changed from the previous version (SQL Server 7). SQL Server uses a set of files to store the data, indexes, and log information for a database. A primary file also has some header information in it, providing SQL Server with necessary information about a database. Each database has a minimum of two files associated with it, one for the data and a second for the log. It is also possible to create multiple files for each of these purposes as described in the following paragraphs. File placement, and object placement within these files, plays an important role in the responsiveness of SQL Server. A database consists of two or more files with each file used for only a single database. A single file cannot be shared by multiple databases. Each database has one or more files used to store indexes and data. The first file created for this purpose is referred to as the primary file. The primary file contains the information needed to start up a database and is also used to store some or all of the data. If desired, secondary files might be created to hold some of the data and other objects. Some databases might be large enough or complex enough in their design to have multiple secondary files used for storage. Normally the log is maintained in a single file. The log file is used to store changes to the database before these changes are recorded in the data files themselves. The storage of information into log files in this manner enables SQL Server to use these files as an important part of its recovery process. Every time the SQL Server is started, it uses the log files for each of the databases to determine what units of work were still being handled at the time the server was stopped.
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