Help Center/ Relational Database Service_RDS for PostgreSQL/ User Guide/ Parameters/ Modifying Parameters of an RDS for PostgreSQL Instance
Updated on 2026-06-15 GMT+08:00
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Modifying Parameters of an RDS for PostgreSQL Instance

You can change parameter values in a custom parameter template and apply it to optimize RDS database performance.

You can only change the values in custom parameter templates. You cannot change the values in default parameter templates.

The following are the key points you should know when using parameters:

  • Modifying instance parameters: If you modify dynamic parameters on the Parameters page of a DB instance and save the modifications, the modifications take effect immediately regardless of the Effective upon Reboot setting. However, if you modify static parameters on the Parameters page of a DB instance and save the modifications, the modifications do not take effect until you manually reboot the DB instance.
  • Modifying parameter template parameters: If you modify parameters in a custom parameter template on the Parameter Templates page and save the modifications, the modifications do not take effect until you apply the template to your DB instances. If you modify static parameters in a custom parameter template on the Parameter Templates page and save the modifications, the modifications do not take effect until you apply the template to your DB instances and manually reboot those DB instances. For details, see Applying a Parameter Template.

When you modify a parameter, the time when modifications take effect varies with the parameter type.

The RDS console displays the statuses of DB instances that the parameter template applies to. For example, if the DB instance has not yet used the latest modifications made to its parameter template, its status is Parameter change. Pending reboot. You need to manually reboot the DB instance for the latest modifications to take effect for that DB instance.

Constraints

RDS has default parameter templates whose parameter values cannot be changed. You can view these parameter values by clicking the default parameter templates. If an instance cannot be started due to incorrect parameter settings of its parameter template, you can reconfigure the parameters based on the default parameter template.

Modifying Instance Parameters

  1. Log in to the RDS console.
  2. Click in the upper left corner and select a region.
  3. On the Instances page, click the target instance name.
  4. In the navigation pane, choose Parameters. On the displayed page, modify parameters as required.

    Allowed operations:

    In the Effective upon Reboot column:
    • If Yes is displayed and the instance status on the Instances page is Parameter change. Pending reboot, a reboot is required to apply the modifications.
      • If you have modified parameters of the primary instance, you must reboot it. (For a primary/standby instance, parameter modifications are also applied to the standby instance.)
      • If you have modified parameters of a read replica, you must reboot the read replica.
    • If No is displayed, the modifications are applied immediately.
    • To save the modifications, click Save.
    • To cancel the modifications, click Cancel.
    • To preview the modifications, click Preview.

    After parameters are modified, you can view the parameter change history of the current instance.

  1. Log in to the RDS console.
  2. Click in the upper left corner and select a region.
  3. In the navigation pane, choose Parameter Templates.
  4. Choose Parameter Templates in the navigation pane on the left. On the Custom Templates page, click the target parameter template.
  5. On the Parameters page, modify parameters as required.

    Allowed operations:

    • To save the modifications, click Save.
    • To cancel the modifications, click Cancel.
    • To preview the modifications, click Preview.

  6. After the parameter values are modified, you can click Change History to view the modification details.
  7. Apply the parameter template to your DB instance. For details, see Applying a Parameter Template.
  8. View the status of the DB instance to which the parameter template has been applied.

    If the DB instance status is Parameter change. Pending reboot, a reboot is required for the modifications to take effect.

    • A DB instance reboot caused by instance class changes will not make parameter modifications take effect.
    • If you have modified parameters of a primary DB instance, you need to reboot the primary DB instance for the modifications to take effect. (For primary/standby DB instances, the parameter modifications are also applied to the standby DB instance.)
    • If you have modified parameters of a read replica, you need to reboot the read replica for the modifications to take effect.

    After parameters are modified, you can view the parameter change history of a custom parameter template.

Viewing Parameter Change History

  1. Log in to the RDS console.
  2. Click in the upper left corner and select a region.
  3. On the Instances page, click the instance name to go to the Summary page.
  4. In the navigation pane, choose Parameters. Then, click the Change History tab.

    Figure 1 Viewing the parameter change history

    You can view the parameter names, original values, new values, modification statuses, modification time, application statuses, and application time on the displayed page.

  1. Log in to the RDS console.
  2. Click in the upper left corner and select a region.
  3. In the navigation pane, choose Parameter Templates.
  4. On the Custom Templates tab page, click the target parameter template name.
  5. On the displayed page, choose Change History in the navigation pane.

    Figure 2 Viewing the parameter change history

    You can view the parameter names, original parameter values, new parameter values, modification statuses, and modification time.

    You can apply this parameter template to DB instances as required by referring to Applying a Parameter Template.

FAQ

Q: Why did my changes to parameters fail to be applied to my instance after I rebooted the instance, and why does the instance status still show Parameter change. Pending reboot?

A: If you change specification parameters, such as work_mem, shared_buffers, and max_connections, to large values, the instance may fail to be started. To ensure that the database runs properly, the system automatically rolls back the parameter change when the database startup fails. Check whether the new values you set are within the allowed ranges. If you do need to set specification parameters to values beyond those ranges, upgrade the instance class first. For details about how to change an instance class, see Changing a DB Instance Class.

Common Parameters

The modifications of some kernel parameters can be applied only after the instance is rebooted. After you modify the parameters on the console, the message "Parameter change. Pending reboot" is displayed.

Figure 3 Modifying parameters
Table 1 Common parameters

Parameter

Description

Reference

timezone

The time zone for displaying and interpreting time stamps.

How Do I Change the Time Zone of an RDS DB Instance?

wal_level

The level of information written to the WAL. This parameter is always set to logical for read replicas.

Does RDS for PostgreSQL Support the test_decoding Extension?

max_connections

The maximum number of concurrent connections.

Instance Guidelines

APIs

Parent Topic: Parameters