Speeding up with LMDB

[vadik6666]

Hi! Did you compare the speed of default torchvision dataset https://pypi.python.org/pypi/torchvision/0.1.8#svhn and your LMDB version?

[Coldmooon]

@vadiklukmanov They are different tasks. The default torchvision dataset requires a single digit prediction, not a sequence of digits.