Configuring a Sparse Backup Policy

Scenarios

RDS for PostgreSQL supports sparse backups in addition to regular backups. It allows you to flexibly configure backup policies in SaaS scenarios and also allows you to retain as few backup sets as possible to reduce expenses.

To enable sparse backup, submit a service ticket to request required permissions.

Differences Between Regular Backup and Sparse Backup

**Table 1** Backup functions
Item	Regular Backup	Sparse Backup
Function description	RDS for PostgreSQL uses regular backup by default. Regular backup backs up all instance data based on the specified time window and backup cycle. A backup file is generated each time a backup is complete, and is stored for the retention period you set.	Compared with the default backup policy, sparse backup reduces the backup frequency while maintaining the same retention period for the backups. After sparse backup is enabled, a regular backup policy is displayed by default. You can add sparse backup policies as needed.
Number of backup policies	An instance has only one backup policy, which cannot be deleted. The default policy is weekly backup. Select at least one day in a week. The backups can be retained for 1 to 732 days.	An instance can have only one regular backup policy and a maximum of nine sparse backup policies. The regular backup policy cannot be deleted, but the sparse backup policies can be deleted. After enabling sparse backup, you can add sparse backup policies alongside the regular backup policy. The regular backup policy is weekly backup and cannot be deleted. Select at least one day in a week. The backups can be retained for 1 to 732 days. There are three types of sparse backup policies. The backups can be retained for 1 to 3,660 days. Weekly: Select at least one day in a week. Monthly: Select at least one day in a month. Yearly: Select a specific day in a year.
Time window	A one-hour period the backup will be scheduled within 24 hours, such as 01:00-02:00 or 12:00-13:00	A one-hour period the backup will be scheduled within 24 hours, such as 01:00-02:00 or 12:00-13:00

Billing

Backups are saved as packages in OBS buckets. For the billing details, see How Is RDS Backup Data Billed?

Configuring a Sparse Backup Policy

Log in to the management console.
Click in the upper left corner and select a region.
Click in the upper left corner of the page and choose Databases > Relational Database Service.
On the Instances page, click the target instance name.
In the navigation pane on the left, choose Backups & Restorations.

In the upper right corner of the page, choose Modify Backup Policy > Configure Same-Region Backup Policy. On the displayed page, you can view the existing backup policy. If you want to modify the policy, adjust the values of the following parameters:

Figure 1 Configuring a sparse backup policy

Time Window: Set it to a one-hour period the backup will be scheduled for each day, such as 01:00-02:00 or 12:00-13:00. The backup time window indicates when the backup starts. The backup duration depends on the data volume of your instance.

To minimize the potential impact on services, set the time window to off-peak hours. The backup time window is saved in the UTC time zone of the local browser. It changes with the time zone during the switch between the DST and standard time.

Sparse Backup Policy

The regular backup policy is weekly backup. Select at least one day in a week. The backups can be retained for 1 to 732 days.

You can add multiple sparse backup policies to back up data by week, month, or year. A maximum of 9 sparse backup policies can be added for a DB instance.

**Table 2** Sparse backup policies
Frequency	Time	Retention Period
Every week	Select at least one day in a week.	The retention period specified in a sparse backup policy applies only to the full automated backups associated with this policy. In a regular backup policy, you can set the retention period to 1 to 732 days. In a sparse backup policy, you can set this period to 1 to 3,660 days. The retention period for incremental backups is determined by the regular backup policy and is irrelevant to sparse backup policies. If you modify the retention period specified in a policy, the modification will be applied to all the existing full automated backups associated with this policy. The retention period specified in any backup policy does not apply to manual backups. Extending the retention period enhances data reliability. Reducing the retention period may cause existing backups to be deleted due to expiration. Exercise caution when performing this operation.
Every month	Select at least one day in a month.
Every year	Select a specific day in a year.

If multiple backup policies need to create backups on the same day, the system generates only one backup on that day. It associates this backup with the policy that has the longest retention period and keeps the backup according to the period specified by that policy.
After sparse backup policies are configured, if no backup is generated in the specified backup window of a day (the backup conflicts with other operations or the backup fails), the backup will be skipped.
When deleting a sparse backup policy, you can choose whether to retain the backups generated under this policy. If you choose not to keep them, all backups created by this policy will be deleted immediately. If you choose to keep them, all these backups will be retained for the original retention period.