On Sat, Oct 17, 2015 at 4:45 AM, Robert Haas <robertmh...@gmail.com> wrote:
> On Fri, Oct 16, 2015 at 2:52 PM, Peter Eisentraut <pete...@gmx.net> wrote: > > The release notes say that checkpoint_segments has been replaced by > > max_wal_size and min_wal_size, but there is no indication on how to > > convert between the old and new settings. I think a lot of people will > > have checkpoint_segments delicately tuned, so we should at least give > > them a hint on how to carry that forward in spirit. > > Yeah, it would be nice to have some guidance about that. But do we > know what the guidance should be? > I think that we should just suggest a reverse formula of the maximum soft limit of checkpoint_segments for max_wal_size in the release notes of 9.5, basically: (3 * your_old_checkpoint_segments + 1) * 16MB = max_wal_size I am not sure it is worth mentioning that one needs to be be sure to keep some extra room to handle potential spikes because that's not a hard limit, but people who have already played with pg_xlog on a different partition are already aware of that after tuning checkpoint_segments. min_wal_size is a new parameter though, I don't think it matters much to hint users for the transfer to the new configuration... Regards, -- Michael
