pg_cron: Job Scheduling
The pg_cron extension is a simple cron-based job scheduler for PostgreSQL that runs inside the database.
pg_cron is not fully supported on Fly Postgres. Read more about this Fly Postgres limitation here.
Usage
Enable the extension
- Go to the Database page in the Dashboard.
- Click on Extensions in the sidebar.
- Search for "pg_cron" and enable the extension.
Syntax
The schedule uses the standard cron syntax, in which * means "run every time period", and a specific number means "but only at this time":
_10 ┌───────────── min (0 - 59)_10 │ ┌────────────── hour (0 - 23)_10 │ │ ┌─────────────── day of month (1 - 31)_10 │ │ │ ┌──────────────── month (1 - 12)_10 │ │ │ │ ┌───────────────── day of week (0 - 6) (0 to 6 are Sunday to_10 │ │ │ │ │ Saturday, or use names; 7 is also Sunday)_10 │ │ │ │ │_10 │ │ │ │ │_10 * * * * *
You can use crontab.guru to help validate your cron schedules.
Scheduling system maintenance
Be extremely careful when setting up pg_cron jobs for system maintenance tasks as they can have unintended consequences. For instance, scheduling a command to terminate idle connections with pg_terminate_backend(pid) can disrupt critical background processes like nightly backups. Often, there is an existing Postgres setting e.g. idle_session_timeout that can perform these common maintenance tasks without the risk.
Reach out to Supabase Support if you're unsure if that applies to your use case.
Examples
Delete data every week
Delete old data on Saturday at 3:30am (GMT):
_10select cron.schedule (_10 'saturday-cleanup', -- name of the cron job_10 '30 3 * * 6', -- Saturday at 3:30am (GMT)_10 $$ delete from events where event_time < now() - interval '1 week' $$_10);
Run a vacuum every day
Vacuum every day at 3:00am (GMT)
_10select cron.schedule('nightly-vacuum', '0 3 * * *', 'VACUUM');
Invoke Supabase Edge Function every minute
Make a POST request to a Supabase Edge Function every minute. Note: this requires the pg_net extension to be enabled.
_13select_13 cron.schedule(_13 'invoke-function-every-minute',_13 '* * * * *', -- every minute_13 $$_13 select_13 net.http_post(_13 url:='https://project-ref.supabase.co/functions/v1/function-name',_13 headers:='{"Content-Type": "application/json", "Authorization": "Bearer YOUR_ANON_KEY"}'::jsonb,_13 body:=concat('{"time": "', now(), '"}')::jsonb_13 ) as request_id;_13 $$_13 );
Edit a job
Changes the frequency of a job called 'vacuum' to once every 5 minutes.
_10select cron.alter_job(_10 job_id := (select jobid from cron.job where jobname = 'vacuum'),_10 schedule := '*/5 * * * *'_10);
Full options for the cron.alter_job() function are:
_10cron.alter_job(_10 job_id bigint,_10 schedule text default null,_10 command text default null,_10 database text default null,_10 username text default null,_10 active boolean default null_10)
Unschedule a job
Unschedules a job called 'nightly-vacuum'
_10select cron.unschedule('nightly-vacuum');
Viewing previously ran jobs
View the last ten jobs that have ran
_10select_10 *_10from cron.job_run_details_10order by start_time desc_10limit 10;
The records in cron.job_run_details are not cleaned automatically which will take up disk space in your datbabase.