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more style docs

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Sarah Hoffmann
2019-01-03 21:08:38 +01:00
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docs/admin/Import-and-Update.md
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@@ -60,7 +60,7 @@ Nominatim can use postcodes from an external source to improve searches that inv
## Choosing the Data to Import ## Choosing the Data to Import
In its default setup, Nominatim is configured to import the full OSM data In its default setup Nominatim is configured to import the full OSM data
set for the entire planet. Such a setup requires a powerful machine with set for the entire planet. Such a setup requires a powerful machine with
at least 32GB of RAM and around 800GB of SSD hard disks. Depending on your at least 32GB of RAM and around 800GB of SSD hard disks. Depending on your
use case there are various ways to reduce the amount of data imported. This use case there are various ways to reduce the amount of data imported. This
@@ -69,15 +69,31 @@ section discusses these methods. They can also be combined.
### Using an extract ### Using an extract
If you only need geocoding for a smaller region, then precomputed extracts If you only need geocoding for a smaller region, then precomputed extracts
are a good way to reduce the database size. are a good way to reduce the database size and import time.
[Geofabrik](https://download.geofabrik.de) offers extracts for most countries [Geofabrik](https://download.geofabrik.de) offers extracts for most countries.
and also daily updates which can be used with the update process described They even have daily updates which can be used with the update process described
below. There are also below. There are also
[other providers for extracts](https://wiki.openstreetmap.org/wiki/Planet.osm#Downloading) [other providers for extracts](https://wiki.openstreetmap.org/wiki/Planet.osm#Downloading).
Please be aware that some extracts are not exactly cut along the country Please be aware that some extracts are not cut exactly along the country
boundaries. As a result some parts of the boundary may be missing and boundaries. As a result some parts of the boundary may be missing which means
Nominatim cannot compute the areas as a result. that cannot compute the areas for some administrative areas.
### Dropping Data Required for Dynamic Updates
About half of the data in Nominatim's database is not really used for serving
the API. It is only there to allow the data to be updated from the latest
changes from OSM. For many uses these dynamic updates are not really required.
If you don't plan to apply updates, the dynamic part of the database can be
safely dropped using the following command:
```
./utils/setup.php --drop
```
Note that you still need to provide for sufficient disk space for the initial
import. So this option is particularly interesting if you plan to transfer the
database or reuse the space later.
### Reverse-only Imports ### Reverse-only Imports
@@ -94,13 +110,28 @@ Nominatim normally sets up a full search database containing administrative
boundaries, places, streets, addresses and POI data. There are also other boundaries, places, streets, addresses and POI data. There are also other
import styles available which only read selected data: import styles available which only read selected data:
* **settings/import-admin.style**
Only import administrative boundaries and places.
* **settings/import-street.style**
Like the admin style but also adds streets.
* **settings/import-address.style**
Import all data necessary to compute addresses down to house number level.
* **settings/import-full.style**
Default style that also includes points of interest.
The style can be changed with the configuration `CONST_Import_Style`.
style Import time DB size after drop To give you an idea of the impact of using the different style, the table
admin 5h 189 GB 20 GB below gives rough estimates of the final database size after import of a
street 2018 planet and after using the `--drop` option. It also shows the time
address needed for the import on a machine with 32GB RAM, 4 CPUS and SSDs.
full
style | Import time | DB size | after drop
----------|--------------|------------|------------
admin | 5h | 189 GB | 20 GB
street | 42h | 396 GB | 174 GB
address | 59h | 497 GB | 251 GB
full | 80h | GB | GB
You can also customize the styles further. For an description of the You can also customize the styles further. For an description of the
style format see [the developement section](../develop/Import.md). style format see [the developement section](../develop/Import.md).

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docs/develop/Import.md
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@@ -22,7 +22,7 @@ The gazetteer style produces a single table `place` with the following rows:
A single OSM object may appear multiple times in this table when it is tagged A single OSM object may appear multiple times in this table when it is tagged
with multiple tags that may constitute a principal tag. Take for example a with multiple tags that may constitute a principal tag. Take for example a
motorway bridge. In OSM, this would be a way which is tagged with motorway bridge. In OSM, this would be a way which is tagged with
`highway=motoway` and `bridge=yes`. This way would appear in the `place` table `highway=motorway` and `bridge=yes`. This way would appear in the `place` table
once with `class` of `highway` and once with a `class` of `bridge`. Thus the once with `class` of `highway` and once with a `class` of `bridge`. Thus the
*uique key* for `place` is (`osm_type`, `osm_id`, `class`). *uique key* for `place` is (`osm_type`, `osm_id`, `class`).