Cloud Spanner - July 21st, 2021 [Feature]

## Feature [Time to live](https://cloud.google.com/spanner/docs/ttl) (TTL) is now available in public preview. This feature lets database administrators periodically delete unneeded data from Cloud Spanner tables, and so decrease storage and backup costs and potentially increase query performance. To use this feature, a database owner defines a [row deletion policy](https://cloud.google.com/spanner/docs/ttl#defining%5Fa%5Frow%5Fdeletion%5Fpolicy) on a table schema.