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chrisckchang/dupe-finder.js

Last active February 16, 2017 15:11
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Aggregation query to find duplicate key values
Raw
dupe-finder.js
// Desired unique index:
// db.collection.ensureIndex({ firstField: 1, secondField: 1 }, { unique: true})
db.collection.aggregate([
{ $group: {
_id: { firstField: "$firstField", secondField: "$secondField" },
uniqueIds: { $addToSet: "$_id" },
count: { $sum: 1 }
}},
{ $match: {
count: { $gt: 1 }
}}
])
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