Chapter 26: SAS Data Libraries

Definition of a SAS Data Library

A SAS data library is a collection of one or more SAS files that are recognized by SAS and that are referenced and stored as a unit. Each file is a member of the library.

The logical concept of a SAS data library remains constant, regardless of the operating environment. In any operating environment where SAS can be installed, the structure for organizing, locating, and managing SAS files is the same.

At the operating environment level, however, a SAS data library has different physical implementations . Most SAS data libraries implement the storage of files in a manner similar to the way the operating environment stores and accesses files.

For instance, in directory-based operating environments, a SAS data library is a group of SAS files that are stored in the same directory and accessed by the same engine. Other files can be stored in the directory, but only the files with file extensions that are assigned by SAS are recognized as part of the SAS data library. Under OS/390 or z/OS, a SAS data library can be implemented as either a bound library in a traditional OS data set or as a directory under UNIX System Services.

SAS files can be any of the following file types:

• SAS data set (SAS data file or SAS data view)

• SAS catalog

• stored compiled SAS program

• SAS utility file

• access descriptors

• multi-dimensional database files such as MDDB, FDB, and DMDB files

• item store files.

Figure 26.1: Types of Files in a SAS Data Library

Each SAS file, in turn , stores information in smaller units that are characteristic of the SAS file type . For example, SAS data sets store information as variables and observations, while SAS catalogs store information in units called entries . SAS determines the type of a file from the context of the SAS program in which the file is created or specified; therefore, a library can contain files with the same name but with different member types.

SAS data libraries can contain files that you create, or they can be one of several special libraries that SAS provides for convenience, support, and customizing capability such as the WORK library. SAS does not limit the number of SAS files you can store in a SAS data library.