PGAudit: Postgres Auditing

PGAudit extends Postgres's built-in logging abilities. It can be used to selectively track activities within your database.

This helps you with:

• Compliance: Meeting audit requirements for regulations
• Security: Detecting suspicious database activity
• Troubleshooting: Identifying and fixing database issues

Enable the extension

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1. Go to the Database page in the Dashboard.
2. Click on Extensions in the sidebar.
3. Search for pgaudit and enable the extension.

-- Enable the "pgaudit" extension
create extension pgaudit;

-- Disable the "pgaudit" extension
drop extension if exists pgaudit;

Configure the extension

PGAudit can be configured with different levels of precision.

PGAudit logging precision:

• Session: Logs activity within a connection, such as a psql connection.
• User: Logs activity by a particular database user (for example, anon or postgres).
• Global: Logs activity across the entire database.
• Object: Logs events related to specific database objects (for example, the auth.users table).

Although Session, User, and Global modes differ in their precision, they're all considered variants of Session Mode and are configured with the same input categories.

Session mode categories

These modes can monitor predefined categories of database operations:

Below is a limited example of how to assign PGAudit to monitor specific categories.

-- log all CREATE, ALTER, and DROP events
... pgaudit.log = 'ddl';

-- log all CREATE, ALTER, DROP, and SELECT events
... pgaudit.log = 'read, ddl';

-- log nothing
... pgaudit.log = 'none';

Session logging

When you are connecting in a session environment, such as a psql connection, you can configure PGAudit to record events initiated within the session.

The Dashboard is a transactional environment and won't sustain a session.

Inside a session, by default, PGAudit will log nothing:

-- returns 'none'
show pgaudit.log;

In the session, you can set the pgaudit.log variable to record events:

-- log CREATE, ALTER, and DROP events
set pgaudit.log = 'ddl';

-- log all CREATE, ALTER, DROP, and SELECT events
set pgaudit.log = 'read, ddl';

-- log nothing
set pgaudit.log = 'none';

User logging

There are some cases where you may want to monitor a database user's actions. For instance, let's say you connected your database to Zapier and created a custom role for it to use:

create user "zapier" with password '<new password>';

You may want to log all actions initiated by zapier, which can be done with the following command:

alter role "zapier" set pgaudit.log to 'all';

To remove the settings, execute the following code:

-- disables role's log
alter role "zapier" set pgaudit.log to 'none';

-- check to make sure the changes are finalized:
select
  rolname,
  rolconfig
from pg_roles
where rolname = 'zapier';
-- should return a rolconfig path with "pgaudit.log=none" present

Global logging

Use global logging cautiously. It can generate many logs and make it difficult to find important events. Consider limiting the scope of what is logged by using session, user, or object logging where possible.

The below SQL configures PGAudit to record all events associated with the postgres role. Since it has extensive privileges, this effectively monitors all database activity.

alter role "postgres" set pgaudit.log to 'all';

To check if the postgres role is auditing, execute the following command:

select
  rolname,
  rolconfig
from pg_roles
where rolname = 'postgres';
-- should return a rolconfig path with "pgaudit.log=all" present

To remove the settings, execute the following code:

alter role "postgres" set pgaudit.log to 'none';

Object logging

To fine-tune what object events PGAudit will record, you must create a custom database role with limited permissions:

create role "some_audit_role" noinherit;

No other Postgres user can assume or login via this role. It solely exists to securely define what PGAudit will record.

Once the role is created, you can direct PGAudit to log by assigning it to the pgaudit.role variable:

alter role "postgres" set pgaudit.role to 'some_audit_role';

You can then assign the role to monitor only approved object events, such as select statements that include a specific table:

grant select on random_table to "some_audit_role";

With this privilege granted, PGAudit will record all select statements that reference the random_table, regardless of who or what actually initiated the event. All assignable privileges can be viewed in the Postgres documentation.

If you would no longer like to use object logging, you will need to unassign the pgaudit.role variable:

-- change pgaudit.role to no longer reference some_audit_role
alter role "postgres" set pgaudit.role to '';

-- view if pgaudit.role changed with the following command:
select
  rolname,
  rolconfig
from pg_roles
where rolname = 'postgres';
-- should return a rolconfig path with "pgaudit.role="

Interpreting Audit Logs

PGAudit was designed for storing logs as CSV files with the following headers:

Referenced from the PGAudit official docs

A log made from the following create statement:

create table account (
  id int primary key,
  name text,
  description text
);

Generates the following log in the Dashboard's Postgres Logs:

 AUDIT: SESSION,1,1,DDL,CREATE TABLE,TABLE,public.account,create table account(
  id int,
  name text,
  description text
); <not logged>

Finding and filtering audit logs

Logs generated by PGAudit can be found in Postgres Logs. To find a specific log, you can use the log explorer. Below is a basic example to extract logs referencing CREATE TABLE events

select
  cast(t.timestamp as datetime) as timestamp,
  event_message
from
  postgres_logs as t
  cross join unnest(metadata) as m
  cross join unnest(m.parsed) as p
where event_message like 'AUDIT%CREATE TABLE%'
order by timestamp desc
limit 100;

Practical examples

Monitoring API events

API requests are already recorded in the API Edge Network logs.

To monitor all writes initiated by the PostgREST API roles:

alter role "authenticator" set pgaudit.log to 'write';

-- the above is the practical equivalent to:
-- alter role "anon" set pgaudit.log TO 'write';
-- alter role "authenticated" set pgaudit.log TO 'write';
-- alter role "service_role" set pgaudit.log TO 'write';

Monitoring the auth.users table

In the worst case scenario, where a privileged roles' password is exposed, you can use PGAudit to monitor if the auth.users table was targeted. It should be stated that API requests are already monitored in the API Edge Network and this is more about providing greater clarity about what is happening at the database level.

Logging auth.user should be done in Object Mode and requires a custom role:

-- create logging role
create role "auth_auditor" noinherit;

-- give role permission to observe relevant table events
grant select on auth.users to "auth_auditor";
grant delete on auth.users to "auth_auditor";

-- assign auth_auditor to pgaudit.role
alter role "postgres" set pgaudit.role to 'auth_auditor';

With the above code, any query involving reading or deleting from the auth.users table will be logged.

Best practices

Disabling excess logging

PGAudit, if not configured mindfully, can log all database events, including background tasks. This can generate an undesirably large amount of logs in a few hours.

The first step to solve this problem is to identify which database users PGAudit is observing:

-- find all users monitored by pgaudit
select
  rolname,
  rolconfig
from pg_roles
where
  exists (
    select
      1
    from UNNEST(rolconfig) as c
    where c like '%pgaudit.role%' or c like '%pgaudit.log%'
  );

To prevent PGAudit from monitoring the problematic roles, you'll want to change their pgaudit.log values to none and pgaudit.role values to empty quotes ''

  -- Use to disable object level logging
  alter role "<role name>" set pgaudit.role to '';

  -- Use to disable global and user level logging
  alter role "<role name>" set pgaudit.log to 'none';

FAQ

Using PGAudit to debug database functions

Technically yes, but it is not the best approach. It is better to check out our function debugging guide instead.

Downloading database logs

In the Logs Dashboard you can download logs as CSVs.

Logging observed table rows

By default, PGAudit records queries, but not the returned rows. You can modify this behavior with the pgaudit.log_rows variable:

--enable
alter role "postgres" set pgaudit.log_rows to 'on';

-- disable
alter role "postgres" set pgaudit.log_rows to 'off';

You should not do this unless you are absolutely certain it is necessary for your use case. It can expose sensitive values to your logs that ideally should not be preserved. Furthermore, if done in excess, it can noticeably reduce database performance.

Logging function parameters

We don't currently support configuring pgaudit.log_parameter because it may log secrets in encrypted columns if you are using pgsodium orVault.

You can upvote this feature request with your use-case if you'd like this restriction lifted.

Does PGAudit support system wide configurations?

PGAudit allows settings to be applied to 3 different database scopes:

Supabase limits full privileges for file system and database variables, meaning PGAudit modifications can only occur at the role level. Assigning PGAudit to the postgres role grants it nearly complete visibility into the database, making role-level adjustments a practical alternative to configuring at the database or system level.

PGAudit's official documentation focuses on system and database level configs, but its docs officially supports role level configs, too.

Resources

• Official PGAudit documentation
• Database Function Logging
• Supabase Logging
• Self-Hosting Logs