Re: Freeze avoidance of very large table. - Mailing list pgsql-hackers

From Amit Kapila
Subject Re: Freeze avoidance of very large table.
Date
Msg-id CAA4eK1J48cwDRuBUfJ1d+B+cstsqETkCnX3B-hSKwYS4SepO4w@mail.gmail.com
Whole thread Raw
In response to Re: Freeze avoidance of very large table.  (Andres Freund <andres@anarazel.de>)
Responses Re: Freeze avoidance of very large table.  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
On Sat, Nov 14, 2015 at 1:19 AM, Andres Freund <andres@anarazel.de> wrote:
> On 2015-10-31 11:02:12 +0530, Amit Kapila wrote:
> > On Thu, Oct 8, 2015 at 11:05 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
> > >
> > > On 1 October 2015 at 23:30, Josh Berkus <josh@agliodbs.com> wrote:
> > >>
> > >> On 10/01/2015 07:43 AM, Robert Haas wrote:
> > >> > On Thu, Oct 1, 2015 at 9:44 AM, Fujii Masao <masao.fujii@gmail.com>
> > wrote:
> > >> >> I wonder how much it's worth renaming only the file extension while
> > >> >> there are many places where "visibility map" and "vm" are used,
> > >> >> for example, log messages, function names, variables, etc.
> > >> >
> > >> > I'd be inclined to keep calling it the visibility map (vm) even if it
> > >> > also contains freeze information.
> > >> >
> >
> > What is your main worry about changing the name of this map, is it
> > about more code churn or is it about that we might introduce new issues
> > or is it about that people are already accustomed to call this map as
> > visibility map?
>
> Several:
> * Visibility map is rather descriptive, none of the replacement terms
>   imo come close. Few people will know what a 'freeze' map is.
> * It increases the size of the patch considerably
> * It forces tooling that knows about the layout of the database
>   directory to change their tools
>

All these points are legitimate.

> On the benfit side the only argument I've heard so far is that it allows
> to disambiguate the format. But, uh, a look at the major version does
> that just as well, for far less trouble.
>
> > It seems to me quite logical for understanding purpose as well.  Any new
> > person who wants to work in this area or is looking into it will always
> > wonder why this map is named as visibility map even though it contains
> > information about visibility of page as well as frozen state of page.
>
> Being frozen is about visibility as well.
>

OTOH being visible doesn't mean page is frozen.  I understand that frozen is
related to visibility, but still it is a separate state of page and used for different
purpose.  I think this is a subjective point and we could go either way, it is
just a matter in which way more people are comfortable.



With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

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