Re: [HACKERS] Broken O(n^2) avoidance in wal segment recycling.

Hi,

I just hit this bad a couple times during some testing. Under load, with
2500 segments to recycle, it took well over a minute.

I think we ought to backpatch a version of this fix. Yes, there've not
been many complaints, but there's no messages during log levels one can
enable without beeing completely flooded, so I don't think it's every
likely to be debugged on a live system.

Noteworth is that this stall due to the O(n^2) happens while holding
ControlFileLock.

I'm inclined to think we should even backpatch this.

Heikki, Michael, any comment?

- Andres