It is very important that the T-SQL scripts being executed by Elastic Jobs be idempotent. This means that if they are run multiple times (by accident or intentionally) they won’t fail and won’t produce unintended results. If an elastic job has some side effects, and gets run more than once, it could fail or cause other unintended consequences (like consuming double the resources needed for a large statistics update). One way to ensure idempotence is to make sure that you check if something already exists before trying to create it.
This takes some getting used to, but once you’re in the habit, you are much better off. Read on for more details on other key concepts.