Explain exceptions inside each_iteration

guides/iteration-how-it-works.md

@@ -20,6 +20,11 @@ SELECT  `products`.* FROM `products` ORDER BY products.id LIMIT 100
 ```sql
 SELECT  `products`.* FROM `products` WHERE (products.id > 2) ORDER BY products.id LIMIT 100
 ```
+## Exceptions inside `each_iteration`
+
+When an unrescued exception happens inside the `each_iteration` block, the job will stop and re-enqueue itself with the last successful cursor. This means that the iteration that failed will be retried with the same parameters and the cursor will only move if that iteration succeeds. This behaviour may be enough for intermittent errors, such as network connection failures, but if your execution is deterministic and you have an error, subsequent iterations will never run.
+
+In other words, if you are trying to process 100 records but you have a problem with the 61st, only the first 60 will be processed.
 
 ## Signals