Smith
for
the variable Name, SAS begins with the first observation and reads
through each one until it reaches the observation that satisfies the
condition.
Smith
for Name directly
without having to read all the prior observations.
where Lastname='Smith'
uses
the composite index because Lastname is the first variable in the
index. That is, the value for Lastname is the first part of the value
that is listed in the index.
3.129.42.134