diff --git a/README.md b/README.md
index 5315aa0..1fbbd7f 100644
--- a/README.md
+++ b/README.md
@@ -208,7 +208,7 @@ to import the whole region you are serving.
 
     ```bash
     osm2pgsql --create --hstore --style roads_import.lua -O flex \
-      -H localhost -d obs -U obs \
+      -H localhost -d obs -U obs -W \
       path/to/downloaded/myarea-latest.osm.pbf 
     ```
 
diff --git a/api/obs/api/db.py b/api/obs/api/db.py
index 00f849d..8830574 100644
--- a/api/obs/api/db.py
+++ b/api/obs/api/db.py
@@ -403,22 +403,22 @@ class Comment(Base):
 
 Comment.author = relationship("User", back_populates="authored_comments")
 User.authored_comments = relationship(
-    "Comment", order_by=Comment.created_at, back_populates="author"
+    "Comment", order_by=Comment.created_at, back_populates="author", passive_deletes=True
 )
 
 Track.author = relationship("User", back_populates="authored_tracks")
 User.authored_tracks = relationship(
-    "Track", order_by=Track.created_at, back_populates="author"
+    "Track", order_by=Track.created_at, back_populates="author", passive_deletes=True
 )
 
 Comment.track = relationship("Track", back_populates="comments")
 Track.comments = relationship(
-    "Comment", order_by=Comment.created_at, back_populates="track"
+    "Comment", order_by=Comment.created_at, back_populates="track", passive_deletes=True
 )
 
 OvertakingEvent.track = relationship("Track", back_populates="overtaking_events")
 Track.overtaking_events = relationship(
-    "OvertakingEvent", order_by=OvertakingEvent.time, back_populates="track"
+    "OvertakingEvent", order_by=OvertakingEvent.time, back_populates="track", passive_deletes=True
 )