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Can MongoDB be altered to make "distinct" include multiple values in a field and treat them individually?

asked 2023-05-18 13:30:32 +0000

lakamha gravatar image

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answered 2023-05-18 13:35:01 +0000

lalupa gravatar image

No, MongoDB cannot be altered to make "distinct" include multiple values in a field and treat them individually. The "distinct" command considers each value in a field as a separate entity and returns only the unique ones. If a field contains multiple values, they will be treated as a single value and will not be split into multiple distinct items.

However, you can use the MongoDB aggregation framework to achieve this behavior. The $unwind operator can be used to split an array field into multiple documents, each with a single value in the field. You can then use the $group and $addToSet operators to get distinct values for that field.

For example, to get distinct values for a field "tags" in a collection "articles" that contains an array of tags, you can use the following pipeline:

db.articles.aggregate([ { $unwind: "$tags" }, { $group: { _id: "$tags", count: { $sum: 1 } } }, { $sort: { count: -1 } } ])

This will return the distinct tags and their counts in descending order.

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Asked: 2023-05-18 13:30:32 +0000

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Last updated: May 18 '23