I have a product node type and a review node type. The review node type has a node reference field that points to product. I can make one product and many users can add through using the node reference URL widget several reviews. I've been deleting the products while the reviews have been sitting orphaned in the database. This hasn't been a problem till I installed the Search API module. Perhaps the error being caused by the Entity module is a bug but those pesky node references have no business existing if the product has been erased or at least they shouldn't be published.
I can think of many solutions to this including never letting a product be deleted so that all content stays in the database till the end of time.
However, I would like to just delete all the reviews when a product is deleted. How do I do this.