If you use alternative
lookup data sets, then indexing your lookup data sets can improve
performance. You should create an index by using the variables that
are appropriate for your geocoding method.
Note: The SASHELP.ZIPCODE data
set and the ZIP4 data set from SAS Maps Online are optimized for use
with the GEOCODE procedure. In addition, data sets that you convert
by using the
%GCDMEL9 and
%MAXMIND autocall macros
are indexed automatically. No modifications are needed for any of
these data sets.
Note: The STREET geocoding lookup
data sets that are provided by SAS are already indexed for the GEOCODE
procedure.
If you use SAS procedures
to copy or move the lookup data sets, any associated indexes are preserved.
However, if you use an operating system utility and do not also copy
or move the index files, any indexes will need to be rebuilt.
For ZIP+4 geocoding,
you should create a simple index on the ZIP variable and a compound
index on the ZIP and ZIP+4 variables.
For RANGE geocoding,
you should sort your lookup data set by the key variable, and then
create a simple index with the key variable. You should sort the range
data set by the beginning IP address variable, and then create two
simple indexes for the beginning and ending IP address variables.