add documentation for external postcode feature

diff --git a/docs/admin/Customization.md b/docs/admin/Customization.md
new file mode 100644 (file)
index 0000000..10c8d3d
--- /dev/null
+++ b/docs/admin/Customization.md
@@ -0,0 +1,71 @@
+# 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>_postcodes.csv`. `<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 `<CC>_postcodes.csv.gz`.
+
+The CSV file must use commas as a delimiter and have a header line. Nominatim
+expects three columns to be present: `postcode`, `lat` and `lon`. All other
+columns are ignored. `lon` and `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](https://www.census.gov/geographies/mapping-files/time-series/geo/tiger-line-file.html)
+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.
+
+  1. Get preprocessed TIGER 2020 data:
+
+        cd $PROJECT_DIR
+        wget https://nominatim.org/data/tiger2020-nominatim-preprocessed.tar.gz
+
+  2. Import the data into your Nominatim database:
+
+        nominatim add-data --tiger-data tiger2020-nominatim-preprocessed.tar.gz
+
+  3. Enable use of the Tiger data in your `.env` by adding:
+
+        echo NOMINATIM_USE_US_TIGER_DATA=yes >> .env
+
+  4. Apply the new settings:
+
+        nominatim refresh --functions
+
+
+See the [developer's guide](../develop/data-sources.md#us-census-tiger) for more
+information on how the data got preprocessed.
+

diff --git a/docs/admin/Import.md b/docs/admin/Import.md
index 6b417ff28c0589e7ab93e06133f80f6b06f194b2..2a9a86e6b6fe8dbb31892fed66b11fb7b8282188 100644 (file)
--- a/docs/admin/Import.md
+++ b/docs/admin/Import.md
@@ -83,15 +83,19 @@ The file is about 400MB and adds around 4GB to the Nominatim database.
     `nominatim refresh --wiki-data --importance`. Updating importances for
     a planet can take a couple of hours.
 
     `nominatim refresh --wiki-data --importance`. Updating importances for
     a planet can take a couple of hours.
 

-### Great Britain, USA postcodes
+### External postcodes

 
 

-Nominatim can use postcodes from an external source to improve searches that
-involve a GB or US postcode. This data can be optionally downloaded into the
-project directory:
+Nominatim can use postcodes from an external source to improve searching with
+postcodes. We provide precomputed postcodes sets for the US (using TIGER data)
+and the UK (using the [CodePoint OpenData set](https://osdatahub.os.uk/downloads/open/CodePointOpen).
+This data can be optionally downloaded into the project directory:

 
     cd $PROJECT_DIR
 
     cd $PROJECT_DIR

-    wget https://www.nominatim.org/data/gb_postcode_data.sql.gz
-    wget https://www.nominatim.org/data/us_postcode_data.sql.gz
+    wget https://www.nominatim.org/data/gb_postcodes.csv.gz
+    wget https://www.nominatim.org/data/us_postcodes.csv.gz
+
+You can also add your own custom postcode sources, see
+[Customization of postcodes](Customization.md#external-postcode-data).

 
 ## Choosing the data to import
 
 
 ## Choosing the data to import
 


@@ -274,33 +278,3 @@ you also need to import these key phrases like this:
 
 Note that this command downloads the phrases from the wiki link above. You
 need internet access for the step.
 
 Note that this command downloads the phrases from the wiki link above. You
 need internet access for the step.

-
-
-## Installing Tiger housenumber data for the US
-
-Nominatim is able to use the official [TIGER](https://www.census.gov/geographies/mapping-files/time-series/geo/tiger-line-file.html)
-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.
-
-  1. Get preprocessed TIGER 2020 data:
-
-        cd $PROJECT_DIR
-        wget https://nominatim.org/data/tiger2020-nominatim-preprocessed.tar.gz
-
-  2. Import the data into your Nominatim database:
-
-        nominatim add-data --tiger-data tiger2020-nominatim-preprocessed.tar.gz
-
-  3. Enable use of the Tiger data in your `.env` by adding:
-
-        echo NOMINATIM_USE_US_TIGER_DATA=yes >> .env
-
-  4. Apply the new settings:
-
-        nominatim refresh --functions
-
-
-See the [developer's guide](../develop/data-sources.md#us-census-tiger) for more
-information on how the data got preprocessed.
-

diff --git a/docs/mkdocs.yml b/docs/mkdocs.yml
index b055e9f02946e16f981ca7012249d4c9cb8d0604..ef2ef9a5cbcf6c16c481a98504009c9a5c6d6098 100644 (file)
--- a/docs/mkdocs.yml
+++ b/docs/mkdocs.yml
@@ -19,6 +19,7 @@ pages:
         - 'Import' : 'admin/Import.md'
         - 'Update' : 'admin/Update.md'
         - 'Deploy' : 'admin/Deployment.md'
         - 'Import' : 'admin/Import.md'
         - 'Update' : 'admin/Update.md'
         - 'Deploy' : 'admin/Deployment.md'

+        - 'Customize Imports' : 'admin/Customization.md'

         - 'Nominatim UI'  : 'admin/Setup-Nominatim-UI.md'
         - 'Advanced Installations' : 'admin/Advanced-Installations.md'
         - 'Migration from older Versions' : 'admin/Migration.md'
         - 'Nominatim UI'  : 'admin/Setup-Nominatim-UI.md'
         - 'Advanced Installations' : 'admin/Advanced-Installations.md'
         - 'Migration from older Versions' : 'admin/Migration.md'