@dispatch(Expr, h5py.Dataset)
def pre_compute(expr, data, scope=None, **kwargs):
    nbytes = data.size * data.dtype.alignment
    comfortable_memory = available_memory() / 4

    if nbytes < comfortable_memory:
        return data.value
    else:
        return data
Bring dataset into memory if it's small relative to memory
dataset/ETHPy150Open blaze/blaze/blaze/compute/h5py.py/pre_compute