+
+# Installing compiled shared library database functions
+
+You probably only need to do this if you are running a large, production instance of openstreetmap-website.
+
+Before installing the functions, it's necessary to install the PostgreSQL server development packages. On Ubuntu this means:
+
+```
+sudo apt-get install postgresql-server-dev-all
+```
+
+On Fedora:
+
+```
+sudo dnf install postgresql-devel
+```
+
+The library then needs compiling.
+
+```
+cd db/functions
+make libpgosm.so
+cd ../..
+```
+
+If you previously installed the SQL versions of these functions, we'll need to delete those before adding the new ones:
+
+```
+psql -d openstreetmap -c "DROP FUNCTION IF EXISTS maptile_for_point"
+psql -d openstreetmap -c "DROP FUNCTION IF EXISTS tile_for_point"
+```
+
+Then we create the functions within each database. We're using `pwd` to substitute in the current working directory, since PostgreSQL needs the full path.
+
+```
+psql -d openstreetmap -c "CREATE FUNCTION maptile_for_point(int8, int8, int4) RETURNS int4 AS '`pwd`/db/functions/libpgosm', 'maptile_for_point' LANGUAGE C STRICT"
+psql -d openstreetmap -c "CREATE FUNCTION tile_for_point(int4, int4) RETURNS int8 AS '`pwd`/db/functions/libpgosm', 'tile_for_point' LANGUAGE C STRICT"
+psql -d openstreetmap -c "CREATE FUNCTION xid_to_int4(xid) RETURNS int4 AS '`pwd`/db/functions/libpgosm', 'xid_to_int4' LANGUAGE C STRICT"
+```