Re: freezing tuples ( was: Why is vacuum_freeze_min_age 100m? )

On Fri, 2009-08-14 at 14:37 -0400, Tom Lane wrote:
> I tend to agree with Josh that you do need to offer two knobs.  But
> expressing the second knob as a fraction (with range 0 to 1) might be
> better than an independent "min" parameter.  As you say, that'd be
> useful to prevent people from setting them inconsistently.

Ok. Any ideas for a name?

Josh suggests "vacuum_freeze_dirty_age" (or perhaps he was using at as a
placeholder). I don't particularly like that name, but I can't think of
anything better without renaming vacuum_freeze_min_age.

> > *: As an aside, these GUCs already have incredibly confusing names, and
> > an extra variable would increase the confusion. For instance, they seem
> > to use "min" and "max" interchangeably.
> 
> Some of them are in fact max's, I believe.

Looking at the definitions of vacuum_freeze_min_age and
autovacuum_freeze_max_age there seems to be almost no distinction
between "min" and "max" in those two names. I've complained about this
before:

http://archives.postgresql.org/pgsql-hackers/2008-12/msg01731.php

I think both are essentially thresholds, so giving them two names with
opposite meaning is misleading.

Regards,Jeff Davis