---
title: "Use parameter groups"
description: "Save PostgreSQL settings in a TIR DBaaS parameter group, attach it to a database from Edit, and detach or delete the group when you are done."
content_type: "how-to"
product: "tir-dbaas"
platform: "TIR"
url: "/tir/tir-dbaas/how-to/use-parameter-groups/"
topic: ["configure"]
---

# 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](/tir/tir-iam/).
- To attach a group, a database in the **Running** state. See [Create a
  database](/tir/tir-dbaas/how-to/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](#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](/tir/tir-dbaas/troubleshooting/tir-dbaas/#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](/tir/tir-dbaas/how-to/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](/tir/tir-dbaas/troubleshooting/tir-dbaas/#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](/tir/tir-dbaas/how-to/edit-a-database/) and [Add
extensions](/tir/tir-dbaas/how-to/add-extensions/). For help with a message, see [Troubleshooting TIR
DBaaS](/tir/tir-dbaas/troubleshooting/tir-dbaas/).