If your CSV file is large has (many columns, such as preceding 50, I even saw 100+) and long (has many lines), you may face an OutOfMemoryException crashing your import. To avoid this, a solution is to make the transaction commit periodically. To benefit from this, just add the following:
USING PERIODIC COMMIT nLOAD CSV ....
Here, the value of n is the number of rows processed by the transaction.
Now, let's import some JSON data!