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  4. Managing Parameter Groups

Managing Parameter Groups

You can perform operations Creating a Parameter Group, Modifying a Parameter Group, Deleting a Parameter Group, and Changing the Parameter Group on the DWS management console.

Parameter Group Overview

A parameter group is a collection of database parameters. You can set the parameters for a database to better adapt to the actual situation and run services. When creating or restoring a data warehouse cluster, you must specify a parameter group for the cluster. Parameters in the specified parameter group are applied to all databases in the cluster. After a cluster is created, you can change its parameter group to another one. However, you may need to restart the cluster to make the new parameter group take effect.

DWS has a default parameter group named Default-Parameter-Group-DWS. The default parameter group cannot be deleted, and its parameters cannot be modified. If you want to modify a parameter value, create a customized parameter group. The parameters in the customized group can be modified.

After clusters created before version 1.2.3 are automatically upgraded to version 1.2.3 or later, parameter values in their parameter groups are set to values in the default parameter group. You can change the parameter group for each cluster.

Parameter Group Parameters

Table 1 Parameter group parameters

Parameter

Description

Default Value

session_timeout

Indicates the timeout interval for idle sessions. The unit is second. Value 0 indicates that the timeout limit is disabled.

600

query_dop

Indicates the user-defined query concurrency.

  • Value 0 indicates that the query concurrency is adaptive.
  • Value 1 indicates that query concurrency is disabled.
  • Value 2 indicates that the query concurrency degree is 2.

0

datestyle

Sets the format with which date and time values will be displayed.

ISO,MDY

failed_login_attempts

If the number of incorrect password attempts reaches the value of this parameter, the account is automatically locked. If this parameter is set to 0, the number of consecutive incorrect password attempts is unlimited.

10

timezone

Indicates the time zone for displaying and interpreting time stamps.

UTC

log_timezone

Sets the time zone used for time stamps written in the server log.

UTC

Creating a Parameter Group

If parameters in the default parameter group cannot meet service requirements, you can customize a parameter group and modify the parameter values to better adapt to services.

To create a parameter group, perform the following steps:

  1. Log in to the management console at https://console.otc.t-systems.com/dws/.
  2. In the navigation tree on the left, click Parameter Group Management.
  3. Click Create Parameter Group and set the following parameters:

    • Database Engine: Select a database engine.
    • Parameter Group Name: Enter the name of the new parameter group.

      Enter 4 to 64 characters. Only letters, digits, hyphens (-), underscores (_), and periods (.) are allowed. The value must start with a letter. Letters are case-insensitive.

    • Description: Enter the description of the new parameter group. This parameter is optional.

      The parameter group description contains 0 to 256 characters and does not support special characters !<>'=&".

    Figure 1 Creating a parameter group

  4. Click OK to start creating the parameter group.

Modifying a Parameter Group

You can modify the parameter values in a user-defined parameter group but cannot modify the parameter values in the default parameter group.

  1. Log in to the management console at https://console.otc.t-systems.com/dws/.
  2. In the navigation tree on the left, click Parameter Group Management.
  3. In the Name column, click the name of the target parameter group. The parameter list is displayed.
  4. Enter a new value in the Value column of the parameter to be modified. After the modification, click Save.

    If you modify a parameter whose Restart Required column shows Yes, you need to restart the cluster after saving the modification for the new parameter values to take effect.

  5. (Optional) If the modified parameters take effect only after the clusters are restarted, select Restart all clusters associated with the parameter group. in the displayed Modification Preview dialog box.

    If you do not select this option, the system saves only the parameter values. Then, you need to manually restart the clusters for the new parameter values to take effect.

    Figure 2 Modification Preview

  6. In the Modification Preview dialog box, confirm the settings and click Save.

Deleting a Parameter Group

You can delete an unnecessary parameter group or a parameter group that is not used for a long time. The default parameter group cannot be deleted. Deleted parameter groups cannot be recovered. Exercise caution when performing this operation.

Before deleting a parameter group, ensure that it is not used by any cluster. Otherwise, it cannot be deleted. If the parameter group is used by a cluster, you need to change the parameter group to another one (the default parameter group is recommended) by performing steps in Changing the Parameter Group and delete the original parameter group.

  1. Log in to the management console at https://console.otc.t-systems.com/dws/.
  2. In the navigation tree on the left, click Parameter Group Management.
  3. In the Operation column of the parameter group to be deleted, click Delete.
  4. In the displayed dialog box, click OK.

Changing the Parameter Group

After a cluster is created, you can change its parameter group. After the change, you may need to restart the cluster to make the new parameter group take effect.

To change a parameter group, perform the following steps:

  1. Log in to the management console at https://console.otc.t-systems.com/dws/.
  2. In the navigation tree on the left, click Cluster Management.
  3. In the Operation column of the target cluster, choose More > Change Parameter Group.
  4. In the Change Parameter Group dialog box, click the drop-down list on the right of New Parameter Group and select a new parameter group.
  5. Click OK.