### PostgreSQL Functions
-There are special database functions required by a (little-used) API call, the migrations and diff replication. The former two are provided as *either* pure SQL functions or a compiled shared library. It is recommended that you start with the pure SQL versions, as described below, and only install the compiled shared library if you are running a production server making a lot of `/changes` API calls or need the diff replication functionality.
-
-If you aren't sure which you need, install the SQL version below.
+We need to install some special functions into the PostgreSQL database:
```
psql -d openstreetmap -f db/functions/functions.sql
After installing this software, you may need to carry out some [configuration steps](CONFIGURE.md), depending on your tasks.
-# Installing compiled shared library database functions
+# Installing compiled shared library database functions (optional)
+
+There are special database functions required by a (little-used) API call, the migrations and diff replication. The former two are provided as *either* pure SQL functions or a compiled shared library. The SQL versions are installed as part of the recommended install procedure above and the shared library versions are recommended only if you are running a production server making a lot of `/changes` API calls or need the diff replication functionality.
-You probably only need to do this if you are running a large, production instance of openstreetmap-website.
+If you aren't sure which you need, stick with the SQL versions.
Before installing the functions, it's necessary to install the PostgreSQL server development packages. On Ubuntu this means: