Another great feature of Cosmos DB is, TTL (Time To Live) support. This is a great option to have if you need a database system with Caching option, or you need to purge your data and you don’t want to develop a function to remove data from your dataset. CosmosDB’s TTL feature is pretty simple, all you need to do is, turn this feature on and declare when data should be removed from your dataset. Best part about TTL in CosmosDB is, CosmosDB does not charge you when it removes the data from your containers so you can use your Request Units for other transactions!
There are two ways to set Time to Live value. You can set the TTL value on a container or you can set it on a specific item by using CosmosDB SDK. TTL value must be in seconds.
TTL timer resets if data gets modified for any reason.
Click through for an example of it in action.