> – it seems we could (should) have one more successful "1s wait, 3s sleep" iteration here, ~727ms somehow wasted in a loop, quite a lot.
I think big chunk from these 727ms were spent between "BEGIN" and "select now(), clock_timestamp(), pg_sleep(3) \watch 1".
Not really – there was indeed ~2s delay between BEGIN and the first pg_sleep query, but those ~727ms is something else.
here we measure the remainder between the beginning of the transaction measured by "now()' and the the beginning of the last successful pg_sleep() query:
It already includes all delays that we had from the beginning of our transaction.
The problem with my question was that I didn't take into attention that '2023-01-13 15:51:18.179579+00' is when the last successful query *started*. So the remainder of our 2-min quota – 00:00:04.727345 – includes the last successful loop (3s of successful query + 1s of waiting), and then we have failed after ~700ms.
In other words, there are no issues here, all good.