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DynamoDB transactions ensure ACID compliance for your database operations by grouping related actions into a single unit of work. This guarantees that either all operations succeed or none do, maintaining the consistency of your data even in the event of an error. Imagine a user placing an order on your e-commerce platform. This process typically involves two critical steps:
  1. Inserting a new record into the “orders” table.
  2. Updating the “inventory” table to decrement the item count.
If the insertion into the orders table succeeds while the inventory update fails, your data becomes inconsistent—an order is recorded without the corresponding adjustment in inventory. Transactions are designed to prevent this scenario by ensuring that both operations are executed together.
With DynamoDB transactions, you can commit all changes as a single atomic operation. If any part of the transaction fails, all changes are rolled back, ensuring that your system remains in a consistent state.
The image illustrates the process of placing an order in an application using DynamoDB, comparing operations with and without transactions. It shows insert and update operations on order and inventory tables.

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How Transactions Work

Transactions in DynamoDB work by bundling together multiple operations. When a transaction is executed, DynamoDB reserves extra capacity—doubling the usual write and read capacity units. One set is used for preparing the transaction, and another is reserved for committing it. This additional capacity requirement is necessary to ensure that all operations within the transaction are coordinated correctly.
Keep in mind that implementing transactions will require additional capacity provisioning compared to non-transactional operations. Plan your capacity accordingly to avoid performance bottlenecks.

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Transactional API Calls

DynamoDB provides two primary API calls to manage transactions:
  • TransactGetItems: Executes one or more GetItem operations in a single transaction.
  • TransactWriteItems: Executes one or more DeleteItem, PutItem, or UpdateItem operations together as one atomic transaction.
These APIs not only ensure that your operations maintain consistency but also help to simplify the error handling process. The integrated nature of these calls means that you don’t have to worry about partial updates leading to data corruption.
The image is a diagram explaining DynamoDB transactions, showing two types of API calls: "TransactGetItems" for GetItem operations and "TransactWriteItems" for DeleteItem, PutItem, and UpdateItem operations.
For more information on best practices when using DynamoDB transactions, consider exploring additional resources such as DynamoDB Documentation. Transcribed by https://otter.ai

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