sql-server - 什么是 NDF 文件？

Question

SQL Server 使用 .mdf 作为数据文件，使用 .ldf 作为日志文件，但是 .ndf 文件是什么？

这些文件有什么好处？

Answer 1

来自Files and Filegroups Architecture

辅助数据文件

辅助数据文件构成除主数据文件之外的所有数据文件。有些数据库可能没有任何辅助数据文件，而其他数据库则有多个辅助数据文件。 建议辅助数据文件的文件扩展名为 .ndf。

同样来自file extension NDF - Microsoft SQL Server secondary data file

参见Understanding Files and Filegroups

Secondary data files are optional, are user-defined, and store user data. Secondary files can be used to spread data across multiple disks by putting each file on a different disk drive. Additionally, if a database exceeds the maximum size for a single Windows file, you can use secondary data files so the database can continue to grow.

The recommended file name extension for secondary data files is .ndf.

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For example, three files, Data1.ndf, Data2.ndf, and Data3.ndf, can be created on three disk drives, respectively, and assigned to the filegroup fgroup1. A table can then be created specifically on the filegroup fgroup1. Queries for data from the table will be spread across the three disks; this will improve performance. The same performance improvement can be accomplished by using a single file created on a RAID (redundant array of independent disks) stripe set. However, files and filegroups let you easily add new files to new disks.