Multi-document transactions in MongoDB

🔹 What are Multi-Document Transactions? A transaction is a group of operations that are executed together as a single unit . In MongoDB, multi-document transactions allow you to: Perform multiple operations Across multiple documents/collections And ensure all succeed or all fail Simple: All operations succeed OR none are applied 🔹 Why Transactions are Needed MongoDB normally works on single-document atomicity But sometimes you need consistency across multiple documents 🔹 Example Bank transfer: Deduct money from Account A Add money to Account B If one fails → rollback everything 🔹 Key Properties (ACID) Transactions follow: Atomicity → all or nothing Consistency → data remains valid Isolation → operations don’t interfere Durability → changes are saved 🔹 How it Works (Concept) Start transaction Perform multiple operations Commit → save changes Abort → rollback changes 🔹 Important Points Works in replica sets and sharded clusters Slightly slower than normal operations Should be used only when needed 🔹 When to Use Financial systems (banking) Order processing Critical multi-step operations 🔹 When NOT to Use Simple operations When single document is enough Simple Understanding Transaction = group of operations Multi-document = across multiple documents Ensures consistency