When only a subset of a data file is needed, it is inefficient to extract all the data and then subset it in a subsequent DATA step. Instead, you can use the DATASOURCE procedure options and statements to extract only needed information from the data file.

The DATASOURCE procedure offers the following subsetting capabilities:

• the INTERVAL= option controls the frequency of data output

• the KEEP or DROP statement selects a subset of time series variables

• the RANGE statement restricts the time range of data

• the WHERE statement selects a subset of cross sections