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POMongoDB MapReduce update in place how to
 

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    <p>*Basically I'm trying to order objects by their score over the last hour.</p> <p>I'm trying to generate an hourly votes sum for objects in my database. Votes are embedded into each object. The object schema looks like this:</p> <pre><code>{ _id: ObjectId score: int hourly-score: int &lt;- need to update this value so I can order by it recently-voted: boolean votes: { "4e4634821dff6f103c040000": { &lt;- Key is __toString of voter ObjectId "_id": ObjectId("4e4634821dff6f103c040000"), &lt;- Voter ObjectId "a": 1, &lt;- Vote amount "ca": ISODate("2011-08-16T00:01:34.975Z"), &lt;- Created at MongoDate "ts": 1313452894 &lt;- Created at timestamp }, ... repeat ... } } </code></pre> <p>This question is actually related to a question I asked a couple of days ago <a href="https://stackoverflow.com/questions/7046462/best-way-to-model-a-voting-system-in-mongodb">Best way to model a voting system in MongoDB</a></p> <p>How would I (can I?) run a MapReduce command to do the following:</p> <ol> <li>Only run on objects with recently-voted = true OR hourly-score > 0.</li> <li>Calculate the sum of the votes created in the last hour.</li> <li>Update hourly-score = the sum calculated above, and recently-voted = false.</li> </ol> <p>I also read <a href="http://blog.boxedice.com/2010/06/21/map-reduce-and-mongodb/" rel="nofollow noreferrer">here</a> that I can perform a MapReduce on the slave DB by running db.getMongo().setSlaveOk() before the M/R command. Could I run the reduce on a slave and update the master DB?</p> <p>Are in-place updates even possible with Mongo MapReduce?</p>
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