Once the shards are generated, you need to merge them before the second pass. If you ran this as a single instance, merging isn't required.
```
$ cd $GOPATH/src/github.com/dgraph-io/dgraph/tools/merge
$ go build . && ./merge --stores ~/dgraph/uids --dest ~/dgraph/final.uids
$ go build . && ./merge --stores ~/dgraph/uids --dest ~/dgraph/uasync.final
```
The above command would iterate over all the directories in `~/dgraph/uids`, and merge their data into one `~/dgraph/uasync.final`.
Note that this merge step is important if you're generating multiple uid intances, because all the loader instances need to have access to global uids list.
#### Second Pass: Data Loader
Now that we have assigned UIDs for all the entities, the data is ready to be loaded.
