Each SAS
library is associated with a library engine. SAS library engines are
software components that form the interface between SAS and the SAS
library. It is the SAS library engine that locates files in a SAS
library and renders the file contents to SAS in a form that it can
recognize. Library engines perform such tasks as:
-
-
listing the files in the library
-
deleting and renaming files
SAS
has a Multi Engine Architecture in order to read to and write from
files in different formats. Each SAS engine has specific processing
characteristics, such as the ability to
-
process a SAS file generated by
an older version of SAS
-
read database files created by
other software programs
-
store and access files on disk
or tape
-
determine how variables and observations
are placed in a file
-
place data into memory from its
physical location
-
transport SAS files between operating
environments
You generally are not
aware of the particular type of engine that is processing data at
any given time. If you issue an instruction that is not supported
by the engine, an error message is displayed in the log. When needed,
you can select a specific engine to perform a task. But usually, you
do not have to specify an engine, because SAS automatically selects
the appropriate one.
More than one engine
might be involved in processing a DATA step; for example, one engine
might be used to input data, and another engine might be used to write
observations to the output data set.
For more information
about library engines, including a list of engines available in Base
SAS,
see About Library Engines.