GAE DataStore python - fetch() vs run()

Question

I saw there are two methods for getting data from the datastore: fetch() and run() Regarding fetch the documentation says: Note: You should rarely need to use this method; it is almost always better to use run() instead.

I don't understand the difference between the two. I am new to GAE and Python, please help me understand. Thanks

It says that run() is asynchronous which I don't understand cause unlike JavaScript, once you run the Python script for the site, the html is frozen, right?

Answer 1

Beginner's advice: until you appreciate the difference, stick with fetch(). There are many other things you probably ought to get comfortable with first before this subtle distinction will bother you.

Answer 2

You can run (with run) multiple datastore queries in parallel to improve latency. This has nothing to do with your resulting HTML. The resulting HTML should be the same.