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eranation/gist:3241616

Created August 2, 2012 22:51
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MongoDB Aggregation Framework way for "select count (distinct fieldName) from someTable" for large collections
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gistfile1.js
//equivalent of "select count (distinct fieldName) from someTable"
db.someCollection.aggregate([{ $group: { _id: "$fieldName"} },{ $group: { _id: 1, count: { $sum: 1 } } } ])
@FedericoHeichou
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db.a.aggregate([{"$match": {"port": 80}}, {"$group": { "_id": "$ip"}}, {"$count": "count"}])

This seems cuter (I added a match too)

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