Explain how Transactions are supported in Cosmos DB?
Cosmos DB supports multi-document transactions, providing atomicity, consistency, isolation, and durability (ACID) guarantees within a single container or across multiple containers within the same database account. Here’s how transactions are supported in Cosmos DB:
- Transactional Execution: Transactions in Cosmos DB allow you to group multiple read and write operations together into a single logical transaction. These operations can span multiple documents and partitions within a container or across multiple containers within the same database account.
- Single-Partition Transactions: By default, transactions in Cosmos DB are limited to a single partition. This means that all documents involved in a transaction must belong to the same partition key value. Within a single partition, transactions provide strong consistency, ensuring that all operations within the transaction are applied atomically and durably.
- Cross-Partition Transactions: Cosmos DB also supports cross-partition transactions, which allow transactions to span multiple partitions within a container or across multiple containers. Cross-partition transactions provide a range of consistency levels, such as bounded staleness or session consistency, to balance performance and availability while ensuring transactional integrity.
- Transactional Guarantees: Cosmos DB ensures that transactions are ACID-compliant, providing the following guarantees:
- Atomicity: All operations within a transaction are treated as a single unit. If any operation within the transaction fails, the entire transaction is rolled back, ensuring that the data remains in a consistent state.
- Consistency: Transactions maintain consistency guarantees within the transactional scope. For single-partition transactions, strong consistency is maintained, while cross-partition transactions provide consistent prefix or session consistency, depending on the chosen isolation level.
- Isolation: Transactions in Cosmos DB provide isolation between concurrent transactions, preventing conflicts and ensuring that each transaction operates independently and sees a consistent view of the data.
- Durability: Once a transaction is committed, the changes made within the transaction are durably stored and can be reliably retrieved in case of failures or restarts.
- Transactional APIs: Cosmos DB provides transactional support through its SDKs and APIs. You can use transactional APIs to define and execute transactions programmatically, ensuring the desired atomicity and consistency guarantees for your data operations.
Transactions in Cosmos DB enable you to maintain data integrity and perform complex operations that require multiple changes across documents or partitions. They provide a reliable and consistent way to handle complex transactional workflows and ensure ACID properties for your data operations.