Read / Write Concerns

Read and write concerns are crucial aspects of data consistency and reliability in MongoDB. They determine the level of acknowledgement required by the database for read and write operations. Understanding these concerns can help you balance performance and data durability based on your application needs.

Read Concern

A read concern determines the consistency level of the data returned by a query. It specifies the version of data that a query should return. MongoDB supports different read concern levels:

Write Concern

A write concern indicates the level of acknowledgment MongoDB should provide when writing data to the database. It ensures that the data has been successfully written and replicated before acknowledging the write operation. The different write concern levels are:

Additionally, the j and wtimeout options can be used to fine-tune the write concern:

By configuring read and write concerns appropriately, you can manage the consistency and durability of your MongoDB database according to your application requirements.