Time to Live (TTL) - (Cosmos DB Advanced Topics)

Time to Live (TTL) is a feature of Cosmos DB that allows you to automatically delete items from a container after a specified period of time. This feature is useful for managing data that has a limited lifespan, such as temporary data, logs, or user sessions. In this tutorial, we'll discuss how to use TTL in Cosmos DB and some best practices.

Syntax

To use TTL in Cosmos DB, you need to set the ttl property of each item to the number of seconds until the item should be deleted. This can be done using the Cosmos DB SDK or the Azure Portal.

Example

Here is an example of how to set a TTL value for an item using the Cosmos DB SDK:

var item = new { 
    id = "my-item", 
    name = "My Item", 
    ttl = 3600 
};

var requestOptions = new ItemRequestOptions() 
{ 
    // enable TTL for this item
    EnableContentResponseOnWrite = true,
    // set the TTL value to 3600 seconds
    Properties = new Dictionary<string, object>() 
    { 
        { "ttl", item.ttl } 
    } 
};

await container.CreateItemAsync(item, requestOptions);

In this example, we're setting the TTL value for an item to 3600 seconds (1 hour).

Explanation

TTL is a useful feature in Cosmos DB that allows you to automatically delete data after a specified period of time. This can help reduce data storage costs and improve query performance by removing old or expired data.

To use TTL in Cosmos DB, you must set the ttl property for each item. When an item's TTL expires, it will be automatically deleted by Cosmos DB.

Use

TTL is useful for managing data that has a limited lifespan, such as temporary data, logs, or user sessions. By setting a TTL value for these items, you can ensure that they are automatically deleted after a certain period of time, reducing storage costs and improving query performance.

Important Points

Here are some important points to keep in mind when using TTL in Cosmos DB:

• TTL is not a replacement for traditional backup and restore procedures.
• Be aware that TTL values are in seconds, so make sure you convert any other time units to seconds before setting the TTL value.
• Monitor the TTL of your data and adjust the TTL value as necessary to avoid deleting data prematurely or keeping data longer than necessary.
• TTL is not suitable for all data types and use cases.

Summary

In this tutorial, we discussed how to use TTL in Cosmos DB to automatically delete data after a specified period of time. We covered the syntax, example, explanation, use, and important points of using TTL in Cosmos DB. By understanding these concepts, you can use TTL to effectively manage data with a limited lifespan.