The consistency level in Azure Cosmos DB determines how quickly you can read data that has been written or inserted into the database, in other words, when you write data to Cosmos DB, the consistency level determines how long it will take for that data to be readable by other operations.The Azure Cosmos DB has five different consistency levels, as follows:
- Bounded staleness
- Consistent prefix
This level provides the highest level of consistency, meaning that all read and write operations are guaranteed to be consistent.
For example, if you write data to Cosmos DB and then immediately read that data, you are guaranteed to get the same data back. However, this level may result in slower performance compared to the other levels.
This level allows some degree of inconsistency in the data, but guarantees that any read operation will not return data that is more than a certain number of versions or time intervals behind the latest write.
For example, if you set the staleness to 5 minutes, any read operation will return data that is at most 5 minutes old.
This level provides a consistent view of data within a single session. If a client establishes a session with Cosmos DB, all read and write operations within that session will be consistent.
For example, if you write data to Cosmos DB and then immediately read that data within the same session, you are guaranteed to get the same data back.
This level guarantees that read operations will always return the most recent write operation, but does not guarantee that all previous write operations will be reflected in the read.
For example, if you write data A, B, and C to Cosmos DB in that order, a read operation may return either A and B, or B and C, but not A and C.
This level provides the lowest level of consistency, meaning that it may take some time for write operations to be reflected in read operations. This level is useful for scenarios where high availability is more important than consistency.
For example, if you write data to Cosmos DB and then immediately read that data, you may not necessarily get the same data back, but the data you do get will eventually reflect all of the write operations
I hope, from all the examples above, you have learned about the Azure Cosmos DB consistency levels. If you like it, share it with your friends and subscribe to the blog and YouTube channel for more articles.