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copied!<p>I would model your requirements with a <em>one-to-many</em> relationship like this:</p> <pre><code>class Player(db.Model): name = db.StringProperty() class DailyHomeruns(db.Model): date = db.DateProperty() counter = db.IntegerProperty() player = db.ReferenceProperty(Player) </code></pre> <p>To retrieve all the <code>DailyHomeruns</code> of a given <code>Player</code> you can do it in this way:</p> <pre><code>daily_homeruns = DailyHomeruns.all().filter('player =', player) .filter('date >', date_start) .filter('date <=', date_end) .order('date') </code></pre> <p><em><strong>Read Requirement</em></strong>: </p> <blockquote> <p>Google App Engine performance queries scales with the size of the result set and not with the size of the data set.</p> </blockquote> <p>This means that if your <em>last 5 years homeruns query</em> set contains in average 800 entities <sup>*</sup>, this query performs the same whether it searches over a thousand entities or a million entities.</p> <p><em><strong>Write Requirement</em></strong>:<br> Writes are slow in Google App Engine but your scenario seems quite trivial and I don't see any possible contention/timeout problem; after all you just need to serially update the <code>DailyHomeruns</code> incrementing the counter for a small number of times per day.</p> <p><em><strong>Other thoughts</em></strong>:<br> If you need to calculate some stats, for example the total number of Homeruns of a given <code>Player</code> ,don't even think to use <a href="http://code.google.com/intl/it/appengine/docs/python/datastore/gqlreference.html" rel="nofollow">GQL</a> for this purpose because it does not provide any aggregate function à la <code>SQL</code>.<br> Instead, you have to design your database upfront, defining a model to store the total count of Homeruns per player.<br> Using the <a href="http://code.google.com/intl/it/appengine/docs/python/datastore/transactions.html#Using_Transactions" rel="nofollow">transactions</a> API, each time you increment the <code>DailyHomeruns</code> you will need to increment the TotalHomeruns entity for that Player.</p> <p><sup>* I have estimated 3 matches per week for 52 weeks multiplied per 5 years</sup></p>

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