Re: Freeze avoidance of very large table.

On Sun, Nov 15, 2015 at 1:47 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> On Sat, Nov 14, 2015 at 1:19 AM, Andres Freund <andres(at)anarazel(dot)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(at)2ndquadrant(dot)com>
>> > wrote:
>> > >
>> > > On 1 October 2015 at 23:30, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>> > >>
>> > >> On 10/01/2015 07:43 AM, Robert Haas wrote:
>> > >> > On Thu, Oct 1, 2015 at 9:44 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)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.

I'm stickin' with what I said before, and what I think Andres is
saying too: renaming the map is a horrible idea. It produces lots of
code churn for no real benefit. We usually avoid such changes, and I
think we should do so here, too.

--
Robert Haas
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