Conversion to SQLite

A Nominatim database can be converted into an SQLite database and used as a read-only source for geocoding queries. This sections describes how to create and use an SQLite database.

Danger

This feature is in an experimental state at the moment. Use at your own risk.

Installing prerequisites

To use a SQLite database, you need to install:

• SQLite (>= 3.30)
• Spatialite (> 5.0.0)
• aiosqlite

On Ubuntu/Debian, you can run:

sudo apt install sqlite3 libsqlite3-mod-spatialite libspatialite7

Install the aiosqlite Python package in your virtual environment:

/srv/nominatim-venv/bin/pip install aiosqlite

Creating a new SQLite database

Nominatim cannot import directly into SQLite database. Instead you have to first create a geocoding database in PostgreSQL by running a regular Nominatim import.

Once this is done, the database can be converted to SQLite with

nominatim convert -o mydb.sqlite

This will create a database where all geocoding functions are available. Depending on what functions you need, the database can be made smaller:

• --without-reverse omits indexes only needed for reverse geocoding
• --without-search omit tables and indexes used for forward search
• --without-details leaves out extra information only available in the details API

Using an SQLite database

Once you have created the database, you can use it by simply pointing the database DSN to the SQLite file:

NOMINATIM_DATABASE_DSN=sqlite:dbname=mydb.sqlite

Please note that SQLite support is only available for the Python frontend. To use the test server with an SQLite database, you therefore need to switch the frontend engine:

nominatim serve --engine falcon

You need to install falcon or starlette for this, depending on which engine you choose.

The CLI query commands and the library interface already use the new Python frontend and therefore work right out of the box.