Without reading any of the doco, it appears to be a job definition called invoice-approval-pipeline that runs every 5 seconds.

The steps are:

1. Get all the pending invoices

2. Set their state to "processing"

3. Call out to an external service/process to do the actual processing, wait for a response.

4. If the response is OK, do something

5. Wait 5 seconds and then start again.

Not sure I love the syntax and the way SQL is embedded between the $$

But it is in the database, can be updated and modified in the same way as all the other stored procedures/functions, allows job control, I assume other control structures for parallel steps etc.

Gonna go read the doco now.

"dollar quoting" is the PostgreSQL way to quote strings with quotes, avoiding double quoting or escape characters. I like to use the tagged version of it, like $sql$ SELECT ... $sql$ to describe what is inside.