Is the upsert option enabled by default in update operations?

In MongoDB, the upsert option is not enabled by default during update operations. When performing an update, if a matching document is not found, the update operation will not create a new document unless the upsert option is explicitly set to true. This is an important aspect of how MongoDB handles updates, allowing developers to have control over whether to create a new document in cases where a match does not exist.

This behavior promotes clarity and predictability, as it ensures that updates only modify existing documents unless specified otherwise. By requiring the upsert option to be set explicitly, developers can avoid unintended data modifications and maintain the integrity of the database.

The upsert functionality can be a powerful feature when you want to insert a new document if it doesn't already exist, but it should be used with consideration to prevent unwanted entries.