X-Git-Url: https://git.openstreetmap.org./nominatim.git/blobdiff_plain/f8f20899a35863876c8dd552f4639d681102ee60..18864afa8aee710a5aa7fe65565711119ca7a663:/docs/admin/Installation.md

diff --git a/docs/admin/Installation.md b/docs/admin/Installation.md
index 8c4c670b..f5411604 100644
--- a/docs/admin/Installation.md
+++ b/docs/admin/Installation.md
@@ -158,6 +158,17 @@ make
 sudo make install
 ```
 
+!!! warning
+    The default installation no longer compiles the PostgreSQL module that
+    is needed for the legacy tokenizer from older Nominatim versions. If you
+    are upgrading an older database or want to run the
+    [legacy tokenizer](../customize/Tokenizers.md#legacy-tokenizer) for
+    some other reason, you need to enable the PostgreSQL module via
+    cmake: `cmake -DBUILD_MODULE=on ../Nominatim`. To compile the module
+    you need to have the server development headers for PostgreSQL installed.
+    On Ubuntu/Debian run: `sudo apt install postgresql-server-dev-<postgresql version>`
+
+
 Nominatim installs itself into `/usr/local` per default. To choose a different
 installation directory add `-DCMAKE_INSTALL_PREFIX=<install root>` to the
 cmake command. Make sure that the `bin` directory is available in your path