What is a transaction in MongoDB?

A transaction in MongoDB is a group of operations that run as a single unit, guaranteeing that either all the operations apply, or none of them do. That means the data stays in a consistent state, even if something goes wrong.

#The core idea

A transaction is needed when preserving the atomicity of actions matters. For example: updating two documents in different collections and being sure it never happens that one gets updated while the other doesn't.

#What a transaction guarantees

• Atomicity, all or nothing
• Consistency of the data
• Isolation of the changes
• Durability, the write won't be lost after commit

#Where it's used

• banking operations
• complex updates across different collections
• operations that need to stay strictly in sync

#Summary

A transaction in MongoDB is a way to run several operations on data as a single indivisible operation, ensuring data integrity and stability.