Contents
How does the upsert function work in MongoDB?
Or in other words, upsert is a combination of update and insert (update + insert = upsert). If the value of this option is set to true and the document or documents found that match the specified query, then the update operation will update the matched document or documents.
What does it mean to have a unique index in MongoDB?
Unique Index and Missing Field¶. If a document does not have a value for the indexed field in a unique index, the index will store a null value for this document. Because of the unique constraint, MongoDB will only permit one document that lacks the indexed field.
Why do I get duplicate key error in MongoDB?
Because of the unique constraint, MongoDB will only permit one document that lacks the indexed field. If there is more than one document without a value for the indexed field or is missing the indexed field, the index build will fail with a duplicate key error.
Can a unique index be specified on a hashed index?
You cannot specify a unique constraint on a hashed index. For a ranged sharded collection, only the following indexes can be unique: the default _id index; however, the _id index only enforces the uniqueness constraint per shard if the _id field is not the shard key or the prefix of the shard key.
When to insert a new document in MongoDB?
Update data if there is a matching document. Insert a new document in case there is no document matches the query criteria. To perform an upsert, you use the following updateMany () method with the upsert option:
Why is my Update Query slow in MongoDB?
Same case apply to Update. It needs to check whether the document exists or not. else update cannot be performed. The case where your update query will slow if your not finding document based on your ObjectId / Indexed field.
Is it possible to do a bulk upsert in pymongo?
I would also be open to someone explaining why doing a bulk upsert is no possible / no a best practice, but please explain what the preferred solution to this sort of problem is. Modern releases of pymongo ( greater than 3.x ) wrap bulk operations in a consistent interface that downgrades where the server release does not support bulk operations.