Azure Cosmos DB consistency levels demystified: Finding the perfect balance between performance and consistency
What are Cosmos DB Consistency Levels?
Cosmos DB is Microsoft's globally distributed database service that supports multiple consistency levels to meet different application needs. Consistency levels determine how data is synchronized across multiple regions and replicas, affecting the performance and consistency of read and write operations.
Major Consistency Levels
Strong Consistency: This is the highest consistency level, where each read operation returns the most recently written data. This means all read operations will see the latest data, but it may affect the latency and throughput of write operations.
Session Consistency: Within the same session, read operations will return the result of the write operations. Read operations in different sessions may see different versions of the data, but within the same session, the data is consistent.
Bounded Staleness: This is the default consistency level, allowing data to have some delay within a specified time frame. Read operations may return slightly outdated data, but this delay is limited.
Consistent Prefix: Read operations will return the latest version of the data, but there may be some data updates that are not completed. This consistency level performs well in terms of read operation latency and throughput.
Eventual Consistency: This is the lowest consistency level, allowing data to be delayed for any period of time. Read operations may return very outdated data, but it will eventually synchronize to the latest version.
Choosing the Appropriate Consistency Level
Choosing the appropriate consistency level depends on your application needs. If you require the highest consistency, you can choose Strong Consistency; if you can accept some delay, you can choose Session Consistency or Eventual Consistency. Selecting the right consistency level can help you find a balance between performance and consistency.