Customization of the Database
This section explains in detail how to configure a Nominatim import and the various means to use external data.
External postcode data
Nominatim creates a table of known postcode centroids during import. This table is used for searches of postcodes and for adding postcodes to places where the OSM data does not provide one. These postcode centroids are mainly computed from the OSM data itself. In addition, Nominatim supports reading postcode information from an external CSV file, to supplement the postcodes that are missing in OSM.
To enable external postcode support, simply put one CSV file per country into
your project directory and name it
<CC> must be the
two-letter country code for which to apply the file. The file may also be
gzipped. Then it must be called
The CSV file must use commas as a delimiter and have a header line. Nominatim
expects three columns to be present:
lon. All other
columns are ignored.
lat must describe the x and y coordinates of the
postcode centroids in WGS84.
The postcode files are loaded only when there is data for the given country
in your database. For example, if there is a
us_postcodes.csv file in your
project directory but you import only an excerpt of Italy, then the US postcodes
will simply be ignored.
As a rule, the external postcode data should be put into the project directory before starting the initial import. Still, you can add, remove and update the external postcode data at any time. Simply run:
nominatim refresh --postcodes
to make the changes visible in your database. Be aware, however, that the changes only have an immediate effect on searches for postcodes. Postcodes that were added to places are only updated, when they are reindexed. That usually happens only during replication updates.
Installing Tiger housenumber data for the US
Nominatim is able to use the official TIGER address set to complement the OSM house number data in the US. You can add TIGER data to your own Nominatim instance by following these steps. The entire US adds about 10GB to your database.
Get preprocessed TIGER 2020 data:
cd $PROJECT_DIR wget https://nominatim.org/data/tiger2020-nominatim-preprocessed.csv.tar.gz
Import the data into your Nominatim database:
nominatim add-data --tiger-data tiger2020-nominatim-preprocessed.csv.tar.gz
Enable use of the Tiger data in your
echo NOMINATIM_USE_US_TIGER_DATA=yes >> .env
Apply the new settings:
nominatim refresh --functions
See the developer's guide for more information on how the data got preprocessed.
Special phrases import
As described in the Importation chapter, it is possible to import special phrases from the wiki with the following command:
nominatim special-phrases --import-from-wiki
But, it is also possible to import some phrases from a csv file. To do so, you have access to the following command:
nominatim special-phrases --import-from-csv <csv file>
Note that the two previous import commands will update the phrases from your database. This means that if you import some phrases from a csv file, only the phrases present in the csv file will be kept into the database. All other phrases will be removed.
If you want to only add new phrases and not update the other ones you can add
--no-replace to the import command. For example:
nominatim special-phrases --import-from-csv <csv file> --no-replace
This will add the phrases present in the csv file into the database without removing the other ones.