Generated columns no longer require the STORED attribute. Without this, the generated column is evaluated at query or index time and doesn't require additional storage or write overhead

## Feature Generated columns no longer require the `STORED` attribute. Without this, the generated column is evaluated at query or index time and doesn't require additional storage or write overhead. For more information, see [Create and manage generated columns](https://cloud.google.com/spanner/docs/generated-column/how-to).