Ah, this is not really what I meant, sorry! In any case, it looks like the main issue here is likely that your examples are so huge that the connection times out while you're adding the examples.
What's in your pre-annotated examples btw? Are you sure you want to be import single examples of 10mb? Unless you're working with images, that's pretty unusual and it'd mean that you end up with a 10mb blob of data in your database, which can easily lead to more problems later on.
Edit: Details and explanation: Command "ner.batch-train" returns MemoryError