The development of Imposm 3 was sponsored by [Omniscale](http://omniscale.com/) and development will continue as resources permit.
Please get in touch if you need commercial support or if you need specific features.
Features
--------
* High-performance
* Diff support
* Custom database schemas
* Generalized geometries
### In detail
- High performance:
Parallel from the ground up. It distributes parsing and processing to all available CPU cores.
- Custom database schemas:
Creates tables for different data types. This allows easier styling and better performance for rendering in WMS or tile services.
- Unify values:
For example, the boolean values `1`, `on`, `true` and `yes` all become ``TRUE``.
- Filter by tags and values:
Only import data you are going to render/use.
- Efficient nodes cache:
It is necessary to store all nodes to build ways and relations. Imposm uses a file-based key-value database to cache this data.
- Generalized tables:
Automatically creates tables with lower spatial resolutions, perfect for rendering large road networks in low resolutions.
- Limit to polygons:
Limit imported geometries to polygons from Shapefiles or GeoJSON, for city/state/country imports.
- Easy deployment:
Single binary with only runtime dependencies to common libs (GEOS, GDAL, SQLite and LevelDB)
- Support for table namespace (PostgreSQL schema)
### Performance ###
Imposm 3 is much faster then Imposm 2 and osm2pgsql.
* Makes full use of all available CPU cores
* Bulk inserts into PostgreSQL with `COPY FROM`
* Efficient intermediate cache for reduced IO load during ways and relations building
Some import times from a Hetzner EX 4S server (Intel i7-2600 CPU @ 3.40GHz, 32GB RAM and 2TB software RAID1 (2x2TB 7200rpm SATA disks)) for imports of a 20.5GB planet PBF (2013-06-14) with generalized tables:
* 6:30h in normal-mode
* 13h in diff-mode
osm2pgsql required between 2-8 days in a [similar benchmark (slide 7)](http://www.geofabrik.de/media/2012-09-08-osm2pgsql-performance.pdf) with a smaller PBF file (~15GB).
Import of Europe 11GB PBF with generalized tables on the same server:
* 2:20h in normal-mode
Benchmarks with SSD are TBD.
Current status
--------------
Imposm 3 is in alpha stadium and there is no official release yet.
The import itself is working however and it was already used for production databases.
### Missing ###
* Documentation
* Updating generalized tables in diff-mode
* Automatic download of diff files
* Tile expire list for re-rendering updated areas
* Background mode for diff-import (update DB in background)
You need a JSON file with the target database mapping. See `example-mapping.json` to get an idea what is possible with the mapping.
Imposm creates all new tables inside the `import` table schema. So you'll have `import.osm_roads` etc. You can change the tables to the `public` schema:
There is a [mailing list at Google Groups](http://groups.google.com/group/imposm) for all questions. You can subscribe by sending an email to: `imposm+subscribe@googlegroups.com`
For commercial support [contact Omniscale](http://omniscale.com/contact).
Development
-----------
The source code is available at: <https://github.com/omniscale/imposm3/>
You can report any issues at: <https://github.com/omniscale/imposm3/issues>
### Test ###
#### Unit tests ####
go test imposm3/...
#### System tests ####
There is a system test that imports and updates OSM data and verifies the database content.
This test is written in Python and requires `nose`, `shapely` and `psycopg2`.
WARNING: It uses your local PostgeSQL database (`import` schema), if you have one. Change the database with the standard PGXXX environment variables.