Thread: How can a Postgres SQL script be automatically run when a new table turns up?
How can a Postgres SQL script be automatically run when a new table turns up?
From
Shaozhong SHI
Date:
When a user load a new table in the Postgres System? Can a script automatically detect it and run?
Regards,
David
Re: How can a Postgres SQL script be automatically run when a new table turns up?
From
Jayadevan M
Date:
When a user load a new table in the Postgres System? Can a script automatically detect it and run?
Are you looking for Even triggers?
Regards,
Jay
Re: How can a Postgres SQL script be automatically run when a new table turns up?
From
Shaozhong SHI
Date:
Hi, Jay,
That looks interesting. Is there an excellent example to do the following?
How to create an event trigger in Postgres? When a user finished loading a new table on to it, the trigger can start off an script 10 minutes after the event?
Regards,
David
On Thu, 13 Jan 2022 at 10:50, Jayadevan M <maymala.jayadevan@gmail.com> wrote:
When a user load a new table in the Postgres System? Can a script automatically detect it and run?Are you looking for Even triggers?Regards,Jay
Re: How can a Postgres SQL script be automatically run when a new table turns up?
From
"David G. Johnston"
Date:
On Thu, Jan 13, 2022 at 8:55 AM Shaozhong SHI <shishaozhong@gmail.com> wrote:
That looks interesting. Is there an excellent example to do the following?How to create an event trigger in Postgres? When a user finished loading a new table on to it, the trigger can start off an script 10 minutes after the event?
IIUC when an event trigger executes it prevents the DLL (create table in this example) from committing - so the only thing the event trigger can meaningfully do is write a record to the database that tells some other piece of software to do something 10 minutes from now. You could have a script execute every minute (say via cron) looking for such a record and when it finds one, and the time is right, it would do its thing. Otherwise it would just stop.
David J.
Re: How can a Postgres SQL script be automatically run when a new table turns up?
From
Miles Elam
Date:
On Thu, Jan 13, 2022 at 4:32 PM David G. Johnston <david.g.johnston@gmail.com> wrote:
On Thu, Jan 13, 2022 at 8:55 AM Shaozhong SHI <shishaozhong@gmail.com> wrote:How to create an event trigger in Postgres? When a user finished loading a new table on to it, the trigger can start off an script 10 minutes after the event?You could have a script execute every minute (say via cron)
Vendor-specific, but on AWS, you can invoke a lambda from RDS or Aurora.
1. An event trigger function runs after CREATE TABLE and invokes a lambda.
2. The lambda calls StartExecution on a step function.
3. In the first step of the step functions, call wait for 10 minutes.
4. In the second step, have the lambda perform whatever operation(s) you need to do.
No polling required, but you'd have to be running in a managed service in the Amazon Cloud.
Similarly, if you are self-hosting and willing/able to write some C code or run some pl/pythonu, you could create an extension/function that performs this logic.
Or again if you are self-managed and go the cron route as suggested by David Johnson, there's the extension pg_cron.
– Miles Elam