supabase/apps/docs/content/guides/database/custom-postgres-config.mdx

---
id: 'customizing-postgres-configs'
title: 'Customizing Postgres configs'
description: 'Configuring Postgres for your Supabase project.'
---

Each Supabase project is a pre-configured Postgres cluster. You can override some configuration settings to suit your needs. This is an advanced topic, and we don't recommend touching these settings unless it is necessary.

<Admonition type="note">

Customizing Postgres configurations provides _advanced_ control over your database, but inappropriate settings can lead to severe performance degradation or project instability.

</Admonition>

### Viewing settings

To list all Postgres settings and their descriptions, run:

```sql
select * from pg_settings;
```

## Configurable settings

### User-context settings

The [`pg_settings`](https://www.postgresql.org/docs/current/view-pg-settings.html) table's `context` column specifies the requirements for changing a setting. By default, those with a `user` context can be changed at the `role` or `database` level with [SQL](https://supabase.com/dashboard/project/_/sql/).

To list all user-context settings, run:

```sql
select * from pg_settings where context = 'user';
```

As an example, the `statement_timeout` setting can be altered:

```sql
alter database "postgres" set "statement_timeout" TO '60s';
```

To verify the change, execute:

```sql
show "statement_timeout";
```

### Superuser settings

Some settings can only be modified by a superuser. Supabase pre-enables the [`supautils` extension](https://supabase.com/blog/roles-postgres-hooks#setting-up-the-supautils-extension), which allows the `postgres` role to retain certain superuser privileges. It enables modification of the below reserved configurations at the `role` level:

| Setting                              | Description                                                                                                                                                  |
| ------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `auto_explain.log_min_duration`      | Logs query plans taking longer than this duration.                                                                                                           |
| `auto_explain.log_nested_statements` | Log nested statements' plans.                                                                                                                                |
| `log_min_messages`                   | Minimum severity level of messages to log.                                                                                                                   |
| `pgaudit.*`                          | Configures the [PGAudit extension](https://supabase.com/docs/guides/database/extensions/pgaudit). The `log_parameter` is still restricted to protect secrets |
| `pgrst.*`                            | [`PostgREST` settings](https://docs.postgrest.org/en/stable/references/configuration.html#db-aggregates-enabled)                                             |
| `plan_filter.*`                      | Configures the [pg_plan_filter extension](https://supabase.com/docs/guides/database/extensions/pg_plan_filter)                                               |
| `session_replication_role`           | Sets the session's behavior for triggers and rewrite rules.                                                                                                  |
| `track_io_timing`                    | Collects timing statistics for database I/O activity.                                                                                                        |

For example, to enable `log_nested_statements` for the postgres role, execute:

```sql
alter role "postgres" set "auto_explain.log_nested_statements" to 'on';
```

To view the change:

```sql
select
  rolname,
  rolconfig
from pg_roles
where rolname = 'postgres';
```

### CLI configurable settings

While many Postgres parameters are configurable directly, some configurations can be changed with the Supabase CLI at the [`system`](https://www.postgresql.org/docs/current/config-setting.html#CONFIG-SETTING-SQL) level.

<Admonition type="caution">

CLI changes permanently overwrite default settings, so `reset all` and `set to default` commands won't revert to the original values.

</Admonition>

#### CLI supported parameters

<Admonition type="tip">

If a setting you need is not yet configurable, [share your use case with us](https://supabase.com/dashboard/support/new)! Let us know what setting you'd like to control, and we'll consider adding support in future updates.

</Admonition>

The following parameters are available for overrides:

1. [effective_cache_size](https://postgresqlco.nf/doc/en/param/effective_cache_size/)
1. [logical_decoding_work_mem](https://postgresqlco.nf/doc/en/param/logical_decoding_work_mem/) (CLI only)
1. [maintenance_work_mem](https://postgresqlco.nf/doc/en/param/maintenance_work_mem/)
1. [max_connections](https://postgresqlco.nf/doc/en/param/max_connections/) (CLI only)
1. [max_locks_per_transaction](https://postgresqlco.nf/doc/en/param/max_locks_per_transaction/) (CLI only)
1. [max_parallel_maintenance_workers](https://postgresqlco.nf/doc/en/param/max_parallel_maintenance_workers/)
1. [max_parallel_workers_per_gather](https://postgresqlco.nf/doc/en/param/max_parallel_workers_per_gather/)
1. [max_parallel_workers](https://postgresqlco.nf/doc/en/param/max_parallel_workers/)
1. [max_replication_slots](https://postgresqlco.nf/doc/en/param/max_replication_slots/) (CLI only)
1. [max_slot_wal_keep_size](https://postgresqlco.nf/doc/en/param/max_slot_wal_keep_size/) (CLI only)
1. [max_standby_archive_delay](https://postgresqlco.nf/doc/en/param/max_standby_archive_delay) (CLI only)
1. [max_standby_streaming_delay](https://postgresqlco.nf/doc/en/param/max_standby_streaming_delay) (CLI only)
1. [max_wal_size](https://postgresqlco.nf/doc/en/param/max_wal_size) (CLI only)
1. [max_wal_senders](https://postgresqlco.nf/doc/en/param/max_wal_senders) (CLI only)
1. [max_worker_processes](https://postgresqlco.nf/doc/en/param/max_worker_processes)(https://postgresqlco.nf/doc/en/param/max_worker_processes/) (CLI only)
1. [session_replication_role](https://postgresqlco.nf/doc/en/param/session_replication_role)(https://postgresqlco.nf/doc/en/param/session_replication_role/)
1. [shared_buffers](https://postgresqlco.nf/doc/en/param/shared_buffers)(https://postgresqlco.nf/doc/en/param/shared_buffers/) (CLI only)
1. [wal_keep_size](https://postgresqlco.nf/doc/en/param/wal_keep_size) (CLI only)
1. [wal_sender_timeout](https://postgresqlco.nf/doc/en/param/wal_sender_timeout) (CLI only)
1. [work_mem](https://postgresqlco.nf/doc/en/param/work_mem/)

#### Managing Postgres configuration with the CLI

To start:

1. [Install](/docs/guides/resources/supabase-cli) Supabase CLI 1.69.0+.
1. [Log in](/docs/guides/cli/local-development#log-in-to-the-supabase-cli) to your Supabase account using the CLI.

To update Postgres configurations, use the [`postgres config`](/docs/reference/cli/supabase-postgres-config) command:

```bash
supabase --experimental \
--project-ref <project-ref> \
postgres-config update --config shared_buffers=250MB
```

By default, the CLI will merge any provided config overrides with any existing ones. The `--replace-existing-overrides` flag can be used to instead force all existing overrides to be replaced with the ones being provided:

```bash
supabase --experimental \
--project-ref <project-ref> \
postgres-config update --config max_parallel_workers=3 \
--replace-existing-overrides
```

### Resetting to default config

To reset a setting to its default value at the database level:

```sql
-- reset a single setting at the database level
alter database "postgres" set "<setting_name>" to default;

-- reset all settings at the database level
alter database "postgres" reset all;
```

For `role` level configurations, you can run:

```sql
alter role "<role_name>" set "<setting_name>" to default;
```

### Considerations

1. Changes through the CLI must restart the database and will cause momentary disruption to existing database connections; in most cases this should not take more than a few seconds.
1. Custom Postgres Config will always override the default optimizations generated by Supabase. When changing compute add-ons, you should also review and update your custom Postgres Config to ensure they remain compatible and effective with the updated compute.
1. Some parameters (e.g. `wal_keep_size`) can increase disk utilization, triggering disk expansion, which in turn can lead to [increases in your bill](/docs/guides/platform/compute-add-ons#disk-io).