Another helpful database trick. I was looking for the best way to start a new series of customer IDs at a set increment. This method worked most effectively and involved a single query in MySQL. Here is the original source: http://stackoverflow.com/questions/8440755/how-to-start-with-a-different-customer-id-in-magento
// Let's say you wanted to start with 5001 ALTER TABLE customer_entity AUTO_INCREMENT = 5001; // That's it!!