Hi yejun,
I didn't see any immediate problems with the first approach which you
listed, I agree it will be more efficient than the second approach.
Depending on the shape of your data you might need to adjust the
number of items which you fetch and delete in a single request (100
could be too
The first approach normally should work. But there is also a very very
small possibility that some of fetched entries are updated during this
call, which will cause the updated values being deleted.
The second approach doesn't actually work on GAE, because query isn't
supported inside a
