diff --git a/doc/source/cli/nova-manage.rst b/doc/source/cli/nova-manage.rst
index 0545d46f61..99bf850801 100644
--- a/doc/source/cli/nova-manage.rst
+++ b/doc/source/cli/nova-manage.rst
@@ -62,9 +62,11 @@ Nova Database
 
 ``nova-manage db archive_deleted_rows [--max_rows <number>] [--verbose] [--until-complete]``
 
-    Move deleted rows from production tables to shadow tables. Specifying
-    --verbose will print the results of the archive operation for any tables
-    that were changed. Specifying --until-complete will make the command run
+    Move deleted rows from production tables to shadow tables. Note that the
+    corresponding rows in the instance_mappings and request_specs tables of the
+    API database are purged when instance records are archived. Specifying
+    --verbose will print the results of the archive operation for any tables that
+    were changed. Specifying --until-complete will make the command run
     continuously until all deleted rows are archived. Use the --max_rows option,
     which defaults to 1000, as a batch size for each iteration.