diff --git a/README.md b/README.md
index 9c370c9..b9a4dbb 100644
--- a/README.md
+++ b/README.md
@@ -33,3 +33,8 @@ Use the `run-import.sh` script to set up the Python environment if needed and im
 ```
 
 This script is suitable for cron jobs as it creates the virtual environment on first run, installs dependencies and reuses the environment on subsequent runs.
+
+The importer handles rotated logs in order from oldest to newest so entries are
+processed exactly once. If you rerun the script, it only ingests records with a
+timestamp newer than the latest one already stored in the database, preventing
+duplicates.