google app engine - How long (max characters) can a datastore entity key_name be? Is it bad to haver very long key_names?

Question

What is the maximum number of characters that can be used to define the key_name of a datastore entity?

Is it bad to have very long key_names?

For example: Lets say we use key_names of a 170 characters, which is the length of a Twitter message 140 plus 10 numeric characters for latitude and 10 for longtitude and 10 for a timestamp.

(Reasoning of such a key_name: So by using such a key_name we can easily and quickly be sure of no duplicate postings, since the same message should not come from the same place and time more than once.)

Answer 1

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