Expiring data by using Amazon Keyspaces Time to Live (TTL)
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. For more information, see How it works: Amazon Keyspaces Time to Live (TTL).
You can set, modify, or disable default TTL settings for new and existing tables by using the console or Cassandra Query Language (CQL). On tables with default TTL configured, you can use Cassandra Query Language (CQL) to override the default TTL settings and apply custom TTL values to rows and columns. For more information, see How to use Time to Live (TTL).
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
