Sigh ... Josh Berkus wrote:
> Further, there's no clear justification why these cannot be set to be > the same as our other freeze ages (which our users also don't > understand), or a constant calculated portion of them, or just a > constant. Calculated portion was my first proposal. The objection that was raised was that there's no actual correlation between Xid consumption rate and multixact consumption rate. That observation is correct; in some use cases multixacts will be consumed faster, in others they will be consumed slower. So there's no way to have multixact cleanup not cause extra autovacuum load if we don't have the parameters. > Since nobody anticipated someone adding a GUC in a minor > release, there was no discussion of this topic that I can find; the new > GUCs were added as a "side effect" of fixing the multixact vacuum issue. > Certainly I would have raised a red flag if the discussion of the new > GUCs hadn't been buried deep inside really long emails. When problems are tough, explanations get long. There's no way around that. I cannot go highlighting text in red hoping that people will read those parts. > Adding new GUCs which nobody has any idea how to set, or can even > explain to new users, is not a service to our users. These should be > removed. I don't think we're going to remove the parameters. My interpretation of the paragraph above is "can we please have some documentation that explains how to set these parameters". To that, the answer is sure, we can. However, I don't have time to write it at this point. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
