Created
February 9, 2014 13:59
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MongoDB corollary of SQL's "SELECT DISTINCT ... GROUP BY"
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| db.events.aggregate( | |
| {'$group' : {_id : "$platform", devices: {"$addToSet" : "$device_id"} } }, | |
| {"$unwind" : "$devices" }, | |
| {"$group" : {_id : "$_id", count: {"$sum" : 1}}} | |
| ) |
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