Factor loader into a database storer and a batch loader

what predictions do we have for how this'll change the memory profile of the ingester? The ingester runs on a m1.small, i.e. ~1.7gb ram, at any given point we've about 1gb free; so I expect this'll be fine, but I'm not sure on a: the size of these files, and b: how many can exist at any one time as I read through this.