How can I do aggregate counts

[Ilya]

How can I build a query that has aggregate counts with groupings?

ex.

SELECT count(city) , city FROM customers group by city

Thanks!

[John Patterson]

You can't.  Its a limitation of the datastore.

Two solutions:

Firstly, you could do the count in memory yourself if the number results is small.  So sort by city and just iterate through counting each.

Secondly, you could precalculate if the number of customers is large.  Every time you add or remove a customer update some sort of CountCustomersByCity entity in a transaction.  This entity may only hold a Map<String, Integer>.

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