# Database Migrations
-Since version 3.7.0 Nominatim offers automatic migrations. Please follow
+Nominatim offers automatic migrations since version 3.7. Please follow
the following steps:
-* stop any updates that are potentially running
-* update Nominatim to the newer version
-* go to your project directory and run `nominatim admin --migrate`
-* (optionally) restart updates
+* Stop any updates that are potentially running
+* Update the backend: `pip install -U nominatim-db`
+* Go to your project directory and run `nominatim admin --migrate`
+* Update the frontend: `pip install -U nominatim-api`
+* (optionally) Restart updates
+
+If you are still using CMake for the installation of Nominatim, then you
+need to update the software in one step before migrating the database.
+It is not recommended to do this while the machine is serving requests.
Below you find additional migrations and hints about other structural and
breaking changes. **Please read them before running the migration.**
If you are migrating from a version <3.6, then you still have to follow
the manual migration steps up to 3.6.
+## 4.4.0 -> master
+
+### New structure for Python packages
+
+The nominatim Python package has been split into `nominatim-db` and `nominatim-api`.
+Any imports need to be adapted accordingly.
+
+If you are running the Python frontend, change the server module from
+`nominatim.server.falcon.server` to `nominatim_api.server.falcon.server`.
+
+If you are using the Nominatim library, all imports need to be changed
+from `nominatim.api.<module>` to `nominatim_api.<module>`.
+
+If you have written custom tokenizers or sanitizers, the appropriate modules
+are now found in `nominatim_db`.
+
+## 4.2.0 -> 4.3.0
+
+### New indexes for reverse lookup
+
+The reverse lookup algorithm has changed slightly to improve performance.
+This change needs a different index in the database. The required index
+will be automatically build during migration. Until the new index is available
+performance of the /reverse endpoint is significantly reduced. You should
+therefore either remove traffic from the machine before attempting a
+version update or create the index manually **before** starting the update
+using the following SQL:
+
+```sql
+CREATE INDEX IF NOT EXISTS idx_placex_geometry_reverse_lookupPlaceNode
+ ON placex USING gist (ST_Buffer(geometry, reverse_place_diameter(rank_search)))
+ WHERE rank_address between 4 and 25 AND type != 'postcode'
+ AND name is not null AND linked_place_id is null AND osm_type = 'N';
+```
+
+## 4.0.0 -> 4.1.0
+
+### ICU tokenizer is the new default
+
+Nominatim now installs the [ICU tokenizer](../customize/Tokenizers.md#icu-tokenizer)
+by default. This only has an effect on newly installed databases. When
+updating older databases, it keeps its installed tokenizer. If you still
+run with the legacy tokenizer, make sure to compile Nominatim with the
+PostgreSQL module, see [Installation](Installation.md#building-nominatim).
+
+### geocodejson output changed
+
+The `type` field of the geocodejson output has changed. It now contains
+the address class of the object instead of the value of the OSM tag. If
+your client has used the `type` field, switch them to read `osm_value`
+instead.
+
+## 3.7.0 -> 4.0.0
+
+### NOMINATIM_PHRASE_CONFIG removed
+
+Custom blacklist configurations for special phrases now need to be handed
+with the `--config` parameter to `nominatim special-phrases`. Alternatively
+you can put your custom configuration in the project directory in a file
+named `phrase-settings.json`.
+
+Version 3.8 also removes the automatic converter for the php format of
+the configuration in older versions. If you are updating from Nominatim < 3.7
+and still work with a custom `phrase-settings.php`, you need to manually
+convert it into a json format.
+
+### PHP utils removed
+
+The old PHP utils have now been removed completely. You need to switch to
+the appropriate functions of the nominatim command line tool. See
+[Introducing `nominatim` command line tool](#introducing-nominatim-command-line-tool)
+below.
+
## 3.6.0 -> 3.7.0
### New format and name of configuration file