indexing: precompute row counts

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

diff --git a/docs/admin/Advanced-Installations.md b/docs/admin/Advanced-Installations.md
index 98a3b64a10572e4ae2b537f54d33656af712b36c..f8232fb29cea6189b36a2ae7d47a8617531813fb 100644 (file)
--- a/docs/admin/Advanced-Installations.md
+++ b/docs/admin/Advanced-Installations.md
@@ -5,6 +5,35 @@ your Nominatim database. It is assumed that you have already successfully
 installed the Nominatim software itself, if not return to the 
 [installation page](Installation.md).
 
+## Importing with a database user without superuser rights
+
+Nominatim usually creates its own PostgreSQL database at the beginning of the
+import process. This makes usage easier for the user but means that the
+database user doing the import needs the appropriate rights.
+
+If you prefer to run the import with a database user with limited rights,
+you can do so by changing the import process as follows:
+
+1. Run the command for database preparation with a database user with
+   superuser rights. For example, to use a db user 'dbadmin' for a
+   database 'nominatim', execute:
+
+   ```
+   NOMINATIM_DATABASE_DSN="pgsql:dbname=nominatim;user=dbadmin" nominatim import --prepare-database
+   ```
+
+2. Grant the import user the right to create tables. For example, foe user 'import-user':
+
+   ```
+   psql -d nominatim -c 'GRANT CREATE ON SCHEMA public TO "import-user"'
+   ```
+
+3. Now run the reminder of the import with the import user:
+
+   ```
+   NOMINATIM_DATABASE_DSN="pgsql:dbname=nominatim;user=import-user" nominatim import --continue import-from-file --osm-file file.pbf
+   ```
+
 ## Importing multiple regions (without updates)
 
 To import multiple regions in your database you can simply give multiple
@@ -36,16 +65,15 @@ which has the following structure:
 
 ```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 +127,9 @@ 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
-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
@@ -109,6 +137,11 @@ 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.
 
+!!! 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
@@ -167,3 +200,45 @@ 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
 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.