Introduction to Backups

What Are Database Backups?

RDS for PostgreSQL automatically creates backups for DB instances during the backup time window. The backups are stored based on a preset retention period (1 to 732 days).

A backup file is generated each time a backup is complete. If the instance fails or data is damaged, you can use the backup file to restore the instance, ensuring data reliability.

Backup Types

RDS for PostgreSQL supports multiple backup types. For details, see Backup Types.

• Full backup: A full backup is to back up all data, even if no data has changed since the last backup.

  Full backup can be initiated manually or automatically.

• Incremental backup: Incremental backups refer to Write-Ahead Logging (WAL) backups. RDS performs an incremental backup every 5 minutes.

Where Data Is Backed Up

• Single-node instance

  A single-node architecture, which is more cost-effective than mainstream primary/standby DB instances. After a backup is triggered, data is backed up from the primary instance and stored as a package on OBS. The backup does not take up storage space of the instance.

• Primary/standby instance

  An HA architecture. In a primary/standby pair, each instance has the same instance class. After a backup is triggered, data is backed up from the primary instance and stored as a package on OBS. The backup does not take up storage space of the instance.

  If a database or table in the primary instance is maliciously or mistakenly deleted, the database or table in the standby instance will also be deleted. In this case, you can only use backups to restore the deleted data.

How Data Is Backed Up

RDS for PostgreSQL automated backup is enabled by default and cannot be disabled. RDS for PostgreSQL performs automated full backups based on the time window and interval specified in the backup policy. It also backs up data modifications made after the most recent automated full or incremental backup every five minutes. When you restore an instance to a point in time, the most recent full backup will be downloaded from OBS for restoration. After the restoration is complete, incremental backups will be replayed to the specified point in time.

Figure 1 How data is backed up

Backup Storage and Billing

Backups are saved as packages in OBS buckets. Backups occupy backup space in OBS. If the free space RDS provides is used up, the additional space required will be billed. For details, see How Is RDS Backup Data Billed?

Deleting Backups