Added note about culling in database cache backend docs.
@@ -195,6 +195,10 @@ In this example, the cache table's name is ``my_cache_table``::
}
}
+Unlike other cache backends, the database cache does not support automatic
+culling of expired entries at the database level. Instead, expired cache
+entries are culled each time ``add()``, ``set()``, or ``touch()`` is called.
+
Creating the cache table
~~~~~~~~~~~~~~~~~~~~~~~~
