Shridhar Daithankar <[EMAIL PROTECTED]> writes: > William Yu wrote: >> This is an intriguing thought which leads me to think about a similar >> solution for even a production server and that's a solid state drive for >> just the WAL. What's the max disk space the WAL would ever take up?
> Maximum number of WAL segments at any time in 2*(number of checkpoint > segments)+1 IIRC. > So if you have 3 checkpoint segments, you can not have more than 7 WAL > segments at any time. Give or take 1. I don't believe that's a *hard* limit. The system tries to schedule checkpoints often enough to prevent WAL from getting bigger than that, but if you had a sufficiently big spike in update activity, it's at least theoretically possible that more than checkpoint_segments segments could be filled before the concurrently running checkpoint finishes and releases some old segments. The odds of this being a real problem are small, especially if you don't try to fit on an undersized SSD by reducing checkpoint_segments. I'd think that a 512Mb SSD would be plenty of space for ordinary update load levels ... regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster