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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| //equivalent of "select count (distinct fieldName) from someTable" | |
| db.someCollection.aggregate([{ $group: { _id: "$fieldName"} },{ $group: { _id: 1, count: { $sum: 1 } } } ]) |
it works!
Nice
Noice!
nice
db.a.aggregate([{"$match": {"port": 80}}, {"$group": { "_id": "$ip"}}, {"$count": "count"}])
This seems cuter (I added a match too)
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Found this ^ when i wanted this: https://gist.github.com/clarkenheim/fa0f9e5400412b6a0f9d
returns a result with the distinct field names, and a count of the documents in the collection which have each distinct field value.