Well, based on your observation it appears that the exception is thrown back to you and by that, without the catch clause it would simply appear in the logs with the entire stack trace which I believe what u are trying to do. If you are able to catch the exception and log it, not sure why it wouldn't show in the logs? would that be due to log4j configuration failing to declare the package? 

Ignoring to catch the exception explicitly does not seem to cause a program crash. So I am not sure I understand the point of catching and logging it, if it's just going to show up in the logs regardless without causing a crash. Unless you were planning to do something about the exception for a remedy...which if the db is down or under heavy load...not sure you can do anything at all. 

Does that make sense?

The null check is different. That's a case of failure which makes sense to me.