| From: | "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> |
|---|---|
| To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>,"Jan Wieck" <JanWieck(at)Yahoo(dot)com> |
| Cc: | "Josh Berkus" <josh(at)agliodbs(dot)com>, "Alvaro Herrera" <alvherre(at)commandprompt(dot)com>, "Robert Haas" <robertmhaas(at)gmail(dot)com>, "pgsql-hackers" <pgsql-hackers(at)postgresql(dot)org>, "Russell Smith" <mr-russ(at)pws(dot)com(dot)au> |
| Subject: | Re: Idea for getting rid of VACUUM FREEZE on cold pages |
| Date: | 2010-06-04 15:13:00 |
| Message-ID: | 4C08D1AC0200002500031F4A@gw.wicourts.gov |
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| Lists: | pgsql-hackers |
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Jan Wieck <JanWieck(at)Yahoo(dot)com> writes:
>> I just see a lot of cost caused by this "safety range". I yet
>> have to see its real value, other than "feel good".
>
> Jan, you don't know what you're talking about. I have repeatedly
> had cases where being able to look at xmin was critical to
> understanding a bug. I *will not* hold still for a solution that
> effectively reduces min_freeze_age to zero.
In my experience with my own environment, I can honestly say that
it's clear that not freezing tuples quickly adds more cost than
running with cassert on. If we had to run in production with one or
the other, I would definitely choose cassert from a performance
perspective; which one would do more to find bugs? Why do we view
them so differently?
-Kevin
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