w option is to request acknowledgement, that the write operation has passed to a specified number of mongod instances.Write concern can include the following fields: WriteConcern is an optional parameter, which is in the form of document expressing the write concern to use if greater then majority. The writeConcern is something we are concerned about, because it is related to the write operation and the atomicity. Here, we can give the writeConcern and the collation also. The complete syntax of db.leteMany() method is as below. But it can have two other parameters also. Now, we have seen the db.leteMany() method earlier with a filter parameter. But, if the write operation concerns multiple documents, it is not guaranteed in MongoDB. Now, if our single document contains multiple sub-documents, it is still guaranteed as atomic and if it fails the automatic rollback will occur, like in the relational databases. These operations are also called write operations, and they are atomic only at a single document level. So, if we have a drop statement, update statement, or a delete statement in MongoDB they are guaranteed to be atomic only at the Single document level. MongoDB was specially created with scalability in mind. MongoDB and other NoSQL databases were never designed for ACID properties. Atomicity is the most important property in ACID and it means that, if there are a series of database operations then either everything occurs or nothing occurs. All traditional Relational databases like Oracle, MySQ L are ACID by nature. Now, ACID means Atomicity, Consistency, Isolation, and Durability. Also, make sure that you have a locally installed MongoDB running through Compass or mongod command.Ītomicity is part of the ACID properties in database. If everything is ok, we will be logged in to the shell. Once we have mongo shell installed on our system, we can go to the terminal and type mongo. We will next learn about the four ways to delete a MongoDB document through Mongo shell. It is easy to setup and you need to make sure that you have added it in the Environment variable in your PC. Please make sure you have downloaded the MongoDB Community Server and installed it. We have used Windows 10 in this tutorial. But in this article, we will learn to delete it through the command-line tool of Mongo shell. We can also delete these documents through the GUI of MongoDB Compass or MongoDB Atlas. The documents are basically JSON objects and there are many ways to delete them. It should be a good habit if you use the db command in mongodb prompt to know which database is currently working and you can be sure before removing the database.MongoDB is the most popular NoSQL database, which stores data as documents. If we want to remove an entire database the following mongodb command can be used: >db.dropDatabase() Remove an entire Database using dropDatabase() The above function returns true, it means that the operation has completed successfully. If we want to remove the entire 'userdetails' collection, including all of its documents the following mongodb command can be used : >db.userdetails.drop() Our database name is 'myinfo' and our collection name is 'userdetails'. It may be a good practice if you execute a find() before removing a document as you can fix criteria for removing the document. Remove() is used to remove a document and a collection. In this page, we are going to discuss how to remove the document and entire collection. We have already learned how to insert records into a collection and also learned how to update the document within a collection based on certain criteria.
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