Use parameter groups

A parameter group is a set of PostgreSQL settings that you save once and attach to your databases. One group can be attached to many databases, and each database uses at most one group. A group stores only the values you change from the defaults.

Before you begin

• A TIR project in Chennai, where parameter groups are offered.
• The permission for the task. You need the DBaaS create permission to make a group, update to edit one or attach it to a database, and delete to delete it. See TIR Access Control.
• To attach a group, a database in the Running state. See Create a database.

Find your parameter groups

In the side menu, under Databases, select Parameter Groups. Each group is listed with its PostgreSQL version, how many values it changes, and how many databases use it. To find a group, type its name in Search parameter group.

Create a parameter group

1. On Manage Parameter Groups, select Create Parameter Group.
2. Enter a Name of 3 to 63 characters. It starts with a lowercase letter and uses lowercase letters, numbers, and hyphens. Two groups in a project can have the same name, so a clear name or a description helps you tell them apart.
3. In Engine & Version, choose the PostgreSQL version of the databases you want to use the group with. A database can use only a group made for its own version, and the group keeps the version you choose here.
4. (Optional) Enter a Description of up to 255 characters.
5. Under Database Parameters, change the values you need. See Set parameter values.
6. Select Create Parameter Group. If the create fails, TIR gives the reason.

Set parameter values

Database Parameters has the parameters of the version you chose, by category. Which parameters exist, their defaults, and the values they accept depend on that version. To find one, search by its name or description in Search parameters.

On a new group, every parameter starts on its default. Set each value the way its parameter takes it: with a switch, from a list of fixed values, or as a number or text within what the parameter accepts. A parameter tagged Read only is fixed. To put a changed parameter back on its default, select Reset to beside it, which names the default value, or empty the box. Once you have changed a value, switch from All to Modified to see only the parameters you changed.

A value the parameter does not accept is flagged with what is wrong, and TIR keeps the group from saving until you fix it. For what each message means, see A parameter value is refused.

Attach a group to a database

Attach a group from Edit Database while the database is Running. Attaching applies the group’s values while the database keeps running. Values that PostgreSQL reads only when it starts take effect at the next restart.

1. Choose Edit in the database’s row menu on the Manage Databases list, or in the three-dot menu on its details page.

2. Open Advanced Settings. In Parameter Group, choose one of the groups made for the database’s PostgreSQL version.

   If that version still needs a group, select Click here to create one for it. The group you create there is chosen for the database.

3. Save the change in one of two ways:

   • To apply the values now and leave the start-up values for the next restart, select Update Database.
   • To have every value take effect at once, select Update & Restart and confirm. The database restarts, open connections are dropped, and applications need to reconnect once it is back.

After Update Database, some values apply only after a restart; to restart later, see Stop, start and restart a database.

To check the result, open the Overview tab: Parameter Group under Configuration names the group. Activity Timeline records “Parameter group attached” with the group’s name.

If the database refuses the group’s values, the group stays unattached, and Edit Database lists it under the changes that failed to save, with the message “Error occurred at backend! Please try after sometime.” See The parameter group could not be attached.

To move a database to another group, choose the other group in Parameter Group the same way.

Detach a group from a database

1. Open Edit Database for the database, and open Advanced Settings.
2. Clear the Parameter Group field.
3. Select Update Database.

Detaching only unlinks the group: the values it applied stay on the database. Activity Timeline records “Parameter group detached” with the group’s name.

Edit a parameter group

1. On Manage Parameter Groups, open the group’s Actions menu and choose Edit.
2. Change the name, the description, or the parameter values. The PostgreSQL version stays as it is.
3. Select Save Changes.

Saving replaces the group’s whole set of changed values, so a value you reset to its default is removed from the group. If the save fails, TIR gives the reason. To drop your changes, select Cancel; the group reopens as it was saved.

A value saved in the group can stop being changeable for its version. TIR then warns you that it cannot keep the value, and saving the group removes it.

Delete a parameter group

You can delete a group once it is detached from every database. A database you delete frees its group once its delete has finished.

Deleting removes the group and its saved settings permanently.

1. On Manage Parameter Groups, open the group’s Actions menu and choose Delete.
2. In Delete Parameter Group, tick the box that reads “I understand and want to delete the parameter group”, followed by the group’s name.
3. Select Delete.

TIR confirms that the group was deleted.

To change other settings of a database, such as storage or extensions, see Edit a database and Add extensions. For help with a message, see Troubleshooting TIR DBaaS.