Expire data with Time to Live (TTL) for Amazon Keyspaces (for Apache Cassandra)

Amazon Keyspaces (for Apache Cassandra) Time to Live (TTL) helps you simplify your application logic and optimize the price of storage by expiring data from tables automatically. Data that you no longer need is automatically deleted from your table based on the Time to Live value that you set.

This makes it easier to comply with data retention policies based on business, industry, or regulatory requirements that define how long data needs to be retained or specify when data must be deleted.

For example, you can use TTL in an AdTech application to schedule when data for specific ads expires and is no longer visible to clients. You can also use TTL to retire older data automatically and save on your storage costs.

You can set a default TTL value for the entire table, and overwrite that value for individual rows and columns. TTL operations don't impact your application's performance. Also, the number of rows and columns marked to expire with TTL doesn't affect your table's availability.

Amazon Keyspaces automatically filters out expired data so that expired data isn't returned in query results or available for use in data manipulation language (DML) statements. Amazon Keyspaces typically deletes expired data from storage within 10 days of the expiration date.

In rare cases, Amazon Keyspaces may not be able to delete data within 10 days if there is sustained activity on the underlying storage partition to protect availability. In these cases, Amazon Keyspaces continues to attempt to delete the expired data once traffic on the partition decreases.

After the data is permanently deleted from storage, you stop incurring storage fees.

You can set, modify, or disable default TTL settings for new and existing tables by using the console, Cassandra Query Language (CQL), or the AWS CLI.

On tables with default TTL configured, you can use CQL statements to override the default TTL settings of the table and apply custom TTL values to rows and columns. For more information, see Use the INSERT statement to set custom Time to Live (TTL) values for new rows and Use the UPDATE statement to edit custom Time to Live (TTL) settings for rows and columns.

TTL pricing is based on the size of the rows being deleted or updated by using Time to Live. TTL operations are metered in units of TTL deletes. One TTL delete is consumed per KB of data per row that is deleted or updated.

For example, to update a row that stores 2.5 KB of data and to delete one or more columns within the row at the same time requires three TTL deletes. Or, to delete an entire row that contains 3.5 KB of data requires four TTL deletes.

One TTL delete is consumed per KB of deleted data per row. For more information about pricing, see Amazon Keyspaces (for Apache Cassandra) pricing.

Amazon Keyspaces Time to Live and integration with AWS services

The following TTL metric is available in Amazon CloudWatch to enable continuous monitoring.

For more information about how to monitor CloudWatch metrics, see Monitoring Amazon Keyspaces with Amazon CloudWatch.

When you use AWS CloudFormation, you can turn on TTL when creating an Amazon Keyspaces table. For more information, see the AWS CloudFormation User Guide.