11.8. Deleting documents in MongoDB: Best practices for deleting documents

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Deleting documents from a MongoDB database is a task that requires attention and care. MongoDB offers several ways to delete documents, each with its own advantages and disadvantages. In this chapter of our e-book, we will discuss best practices for deleting documents in MongoDB.

1. Understand what you are deleting

Before deleting any document, it's important to understand what you are deleting. This may seem obvious, but many deletion errors occur because the developer didn't fully understand what they were deleting. Therefore, before deleting any document, make sure you understand what the document contains and how it is related to other documents in the database.

2. Use the deleteOne() method

The deleteOne() method is the most basic method for deleting documents in MongoDB. It deletes the first document that matches the given query criteria. Although it is simple to use, care must be taken when using it as it only deletes one document at a time. If there are multiple documents that match the query criteria, only the first one will be deleted.

3. Use the deleteMany() method

If you need to delete multiple documents that match a query criteria, you can use the deleteMany() method. This method deletes all documents that match the given query criteria. However, care should be taken when using it as it may result in deleting too many documents at once.

4. Use the findOneAndDelete() method

The findOneAndDelete() method is similar to the deleteOne() method, but it also returns the deleted document. This can be useful if you need a copy of the document you are deleting. However, this method is slower than the deleteOne() method because it needs to return the document before deleting it.

5. Use the drop() method

If you need to delete an entire collection, you can use the drop() method. This method deletes the entire collection, including all its documents and indexes. However, care should be taken when using it as it permanently deletes the entire collection.

6. Use the remove() method

The remove() method is an older way of deleting documents in MongoDB. It deletes all documents that match the given query criteria. However, this method has been deprecated in version 3.2 of MongoDB and should not be used in new projects.

7. Always make a backup before deleting

Before deleting any documents, it is good practice to make a database backup. This allows you to restore the database if something goes wrong during the deletion. MongoDB offers several tools for backing up databases, including mongodump and mongoexport.

8. Test your delete query before running it

Before running a delete query, it is good practice to test it first. You can do this by running the query as a select query and checking the results. This allows you to see which documents will be deleted before you actually delete them.

In conclusion, deleting documents in MongoDB is a task that must be done with care. By following the best practices discussed in this chapter, you can ensure that document deletion is done effectively and securely.

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6311.9. Deleting documents in MongoDB: Impact of deleting documents on database performance