diff --git a/docs/ref/databases.txt b/docs/ref/databases.txt
index 15acc2c8f0..0f183bfe20 100644
--- a/docs/ref/databases.txt
+++ b/docs/ref/databases.txt
@@ -154,6 +154,11 @@ password from the `password file`_, you must specify them in the
     Support for connecting by a service name, and specifying a password file
     was added.
 
+.. warning::
+
+    Using a service name for testing purposes is not supported. This
+    :ticket:`may be implemented later <33685>`.
+
 Optimizing PostgreSQL's configuration
 -------------------------------------