Why are key related queries free?

Question

In accordance with the price documents here , the request keys-onlyis free. Thus, it seems that you can save the reading by doing the following (pseudocode):

qo = ndb.QueryOptions(keys_only = True)
qry = ModelName.query().filter("name" = "Bob")
keys = qry.fetch(20, options = qo) #keys-only fetch

Then after that I can get my entities by evaluating 1 reading per entity:

entities = ndb.get_multi(keys)

Why is this considered better than fetching objects (i.e. fetching only for keys)?

Also, where does the request come from? When is it running fetchor when is an object querycreated?

Answer 1

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