Merge pull request #3252 from kumarUjjawal/patch-1

[nominatim.git] / docs / admin / Advanced-Installations.md

diff --git a/docs/admin/Advanced-Installations.md b/docs/admin/Advanced-Installations.md
index ee38f3e4d5dc5a452372400751c0269da9660850..3b98fec39579a5b286542349525bcd1bd63bcc5f 100644 (file)
--- a/docs/admin/Advanced-Installations.md
+++ b/docs/admin/Advanced-Installations.md
@@ -36,16 +36,15 @@ which has the following structure:
 
 ```bash
 update
 
 ```bash
 update

-    ├── europe
-    │   ├── andorra
-    │   │   └── sequence.state
-    │   └── monaco
-    │       └── sequence.state
-    └── tmp
-        └── europe
-                ├── andorra-latest.osm.pbf
-                └── monaco-latest.osm.pbf
-
+ ├── europe
+ │    ├── andorra
+ │    │    └── sequence.state
+ │    └── monaco
+ │         └── sequence.state
+ └── tmp
+      └── europe
+           ├── andorra-latest.osm.pbf
+           └── monaco-latest.osm.pbf

 
 ```
 
 
 ```
 


@@ -99,9 +98,9 @@ Change into the project directory and run the following command:
 
 This will get diffs from the replication server, import diffs and index
 the database. The default replication server in the
 
 This will get diffs from the replication server, import diffs and index
 the database. The default replication server in the

-script([Geofabrik](https://download.geofabrik.de)) provides daily updates.
+script ([Geofabrik](https://download.geofabrik.de)) provides daily updates.

 
 

-## Importing Nominatim to an external PostgreSQL database
+## Using an external PostgreSQL database

 
 You can install Nominatim using a database that runs on a different server when
 you have physical access to the file system on the other server. Nominatim
 
 You can install Nominatim using a database that runs on a different server when
 you have physical access to the file system on the other server. Nominatim


@@ -109,6 +108,11 @@ uses a custom normalization library that needs to be made accessible to the
 PostgreSQL server. This section explains how to set up the normalization
 library.
 
 PostgreSQL server. This section explains how to set up the normalization
 library.
 

+!!! note
+    The external module is only needed when using the legacy tokenizer.
+    If you have chosen the ICU tokenizer, then you can ignore this section
+    and follow the standard import documentation.
+

 ### Option 1: Compiling the library on the database server
 
 The most sure way to get a working library is to compile it on the database
 ### Option 1: Compiling the library on the database server
 
 The most sure way to get a working library is to compile it on the database


@@ -166,4 +170,46 @@ NOMINATIM_DATABASE_MODULE_PATH="<directory on the database server where nominati
 ```
 
 Now change the `NOMINATIM_DATABASE_DSN` to point to your remote server and continue
 ```
 
 Now change the `NOMINATIM_DATABASE_DSN` to point to your remote server and continue

-to follow the [standard instructions for importing](/admin/Import).
+to follow the [standard instructions for importing](Import.md).
+
+
+## Moving the database to another machine
+
+For some configurations it may be useful to run the import on one machine, then
+move the database to another machine and run the Nominatim service from there.
+For example, you might want to use a large machine to be able to run the import
+quickly but only want a smaller machine for production because there is not so
+much load. Or you might want to do the import once and then replicate the
+database to many machines.
+
+The important thing to keep in mind when transferring the Nominatim installation
+is that you need to transfer the database _and the project directory_. Both
+parts are essential for your installation.
+
+The Nominatim database can be transferred using the `pg_dump`/`pg_restore` tool.
+Make sure to use the same version of PostgreSQL and PostGIS on source and
+target machine.
+
+!!! note
+    Before creating a dump of your Nominatim database, consider running
+    `nominatim freeze` first. Your database looses the ability to receive further
+    data updates but the resulting database is only about a third of the size
+    of a full database.
+
+Next install Nominatim on the target machine by following the standard installation
+instructions. Again, make sure to use the same version as the source machine.
+
+Create a project directory on your destination machine and set up the `.env`
+file to match the configuration on the source machine. Finally run
+
+    nominatim refresh --website
+
+to make sure that the local installation of Nominatim will be used.
+
+If you are using the legacy tokenizer you might also have to switch to the
+PostgreSQL module that was compiled on your target machine. If you get errors
+that PostgreSQL cannot find or access `nominatim.so` then rerun
+
+   nominatim refresh --functions
+
+on the target machine to update the the location of the module.