Re: Redesigning checkpoint_segments

Instead of "running out of disk space PANIC" we should just write to an emergency location within PGDATA

This merely buys you some time, but with aggressive and sustained write throughput you are left on the same spot. Practically speaking it's the same situation as increasing the pg_xlog disk space.

Except that you likely can't increase pg_xlog space (easily). The point here is to have overflow, think swap space.

I agree it is better than PANIC, but read-only mode is definitely also a form of throttling; a much more abrupt and unfriendly one if I may add.

I would think read only is less unfriendly than an all out failure. Consider if done correctly, the database would move back into read-write mode once the problem was resolved.

JD