mongodb unique index array
To index a field that holds an array value, MongoDB creates an index key for each element in the array. This suggests that arrays are not indexed as single objects, but are unwinded into multiple objects.,MongoDB uses multikey indexes to index the content stored in arrays. If you index a field that holds an array value, MongoDB creates separate index entries for every element of the array. These multikey indexes allow queries to select documents that conta, That is because, an index is unique across a collection of documents. The subdocuments are not really documents, a document is forced to ..., The array index will not meet your requirement. But I think you can switch to the other format to store your data. If there is no need to use the ..., you cannot enforce complete uniqueness when it comes to arrays. As far as I know, unique indexes only enforce uniqueness across different ..., You're correct that the restrictions of the unique index is as you described. However, that is only true for a singular value field. Once you use ..., As far as I know, unique indexes only enforce uniqueness across different documents, so this would throw a duplicate key error: db.cats.insert( ...,To index a field that holds an array value, MongoDB creates an index key for ... for a unique multikey index, a document may have array elements that result in ... , I am finding that a unique index is not applied to multiple elements of an array in the same document of a collection. They are only applied ...,You can also enforce a unique constraint on compound indexes. If you use the unique constraint on a compound index, then MongoDB will enforce uniqueness on the combination of the index key values. The created index enforces uniqueness for the combination
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 mongodb unique index array 相關參考資料
arrays - Unique index in MongoDB - Stack Overflow
To index a field that holds an array value, MongoDB creates an index key for each element in the array. This suggests that arrays are not indexed as single objects, but are unwinded into multiple obj... https://stackoverflow.com Indexes — MongoDB Manual
MongoDB uses multikey indexes to index the content stored in arrays. If you index a field that holds an array value, MongoDB creates separate index entries for every element of the array. These multik... https://docs.mongodb.com indexing - Add an unique index to an array type field in embed ...
That is because, an index is unique across a collection of documents. The subdocuments are not really documents, a document is forced to ... https://stackoverflow.com indexing - Unique Index on Array in MongoDB - Stack Overflow
The array index will not meet your requirement. But I think you can switch to the other format to store your data. If there is no need to use the ... https://stackoverflow.com mongodb - How to add a unique index on an embedded array in Mongo ...
you cannot enforce complete uniqueness when it comes to arrays. As far as I know, unique indexes only enforce uniqueness across different ... https://stackoverflow.com mongodb - Unique compound index on array fields - Stack Overflow
You're correct that the restrictions of the unique index is as you described. However, that is only true for a singular value field. Once you use ... https://stackoverflow.com MongoDB: Unique index on array element's property - Stack Overflow
As far as I know, unique indexes only enforce uniqueness across different documents, so this would throw a duplicate key error: db.cats.insert( ... https://stackoverflow.com Multikey Indexes — MongoDB Manual
To index a field that holds an array value, MongoDB creates an index key for ... for a unique multikey index, a document may have array elements that result in ... https://docs.mongodb.com unique indexes not enforced within array of single ... - mongoDB jira
I am finding that a unique index is not applied to multiple elements of an array in the same document of a collection. They are only applied ... https://jira.mongodb.org Unique Indexes — MongoDB Manual
You can also enforce a unique constraint on compound indexes. If you use the unique constraint on a compound index, then MongoDB will enforce uniqueness on the combination of the index key values. The... https://docs.mongodb.com |