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

From Andres Freund
Subject Re: Freeze avoidance of very large table.
Date
Msg-id 20151113194916.GC10369@alap3.anarazel.de
Whole thread Raw
In response to Re: Freeze avoidance of very large table.  (Amit Kapila <amit.kapila16@gmail.com>)
Responses Re: Freeze avoidance of very large table.  (Amit Kapila <amit.kapila16@gmail.com>)
List pgsql-hackers
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

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.

Greetings,

Andres Freund



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