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

<br /><br /> On Tue, Nov 17, 2015 at 10:45 AM, Robert Haas <<a href="javascript:;">robertmhaas@gmail.com</a>>
wrote:<br/> > On Sun, Nov 15, 2015 at 1:47 AM, Amit Kapila <<a
href="javascript:;">amit.kapila16@gmail.com</a>>wrote:<br /> >> On Sat, Nov 14, 2015 at 1:19 AM, Andres Freund
<<ahref="javascript:;">andres@anarazel.de</a>> wrote:<br /> >>> On 2015-10-31 11:02:12 +0530, Amit
Kapilawrote:<br /> >>> > On Thu, Oct 8, 2015 at 11:05 PM, Simon Riggs <<a
href="javascript:;">simon@2ndquadrant.com</a>><br/> >>> > wrote:<br /> >>> > ><br />
>>>> > On 1 October 2015 at 23:30, Josh Berkus <<a href="javascript:;">josh@agliodbs.com</a>>
wrote:<br/> >>> > >><br /> >>> > >> On 10/01/2015 07:43 AM, Robert Haas wrote:<br
/>>>> > >> > On Thu, Oct 1, 2015 at 9:44 AM, Fujii Masao <<a
href="javascript:;">masao.fujii@gmail.com</a>><br/> >>> > wrote:<br /> >>> > >>
>>I wonder how much it's worth renaming only the file extension<br /> >>> > >> >>
while<br/> >>> > >> >> there are many places where "visibility map" and "vm" are used,<br />
>>>> >> >> for example, log messages, function names, variables, etc.<br /> >>> >
>>><br /> >>> > >> > I'd be inclined to keep calling it the visibility map (vm) even
if<br/> >>> > >> > it<br /> >>> > >> > also contains freeze information.<br
/>>>> > >> ><br /> >>> ><br /> >>> > What is your main worry about
changingthe name of this map, is it<br /> >>> > about more code churn or is it about that we might
introducenew issues<br /> >>> > or is it about that people are already accustomed to call this map as<br />
>>>> visibility map?<br /> >>><br /> >>> Several:<br /> >>> * Visibility map is
ratherdescriptive, none of the replacement terms<br /> >>>   imo come close. Few people will know what a
'freeze'map is.<br /> >>> * It increases the size of the patch considerably<br /> >>> * It forces
toolingthat knows about the layout of the database<br /> >>>   directory to change their tools<br />
>>><br/> >><br /> >> All these points are legitimate.<br /> >><br /> >>> On the
benfitside the only argument I've heard so far is that it allows<br /> >>> to disambiguate the format. But,
uh,a look at the major version does<br /> >>> that just as well, for far less trouble.<br /> >>><br
/>>>> > It seems to me quite logical for understanding purpose as well.  Any new<br /> >>> >
personwho wants to work in this area or is looking into it will always<br /> >>> > wonder why this map is
namedas visibility map even though it contains<br /> >>> > information about visibility of page as well as
frozenstate of page.<br /> >>><br /> >>> Being frozen is about visibility as well.<br />
>>><br/> >><br /> >> OTOH being visible doesn't mean page is frozen.  I understand that frozen
is<br/> >> related to visibility, but still it is a separate state of page and used for<br /> >>
different<br/> >> purpose.  I think this is a subjective point and we could go either way, it<br /> >>
is<br/> >> just a matter in which way more people are comfortable.<br /> ><br /> > I'm stickin' with what I
saidbefore, and what I think Andres is<br /> > saying too: renaming the map is a horrible idea.  It produces lots
of<br/> > code churn for no real benefit.  We usually avoid such changes, and I<br /> > think we should do so
here,too.<br /><br /> I understood.<br /> I'm going to turn the patch back to visibility map, and just add the logic of
enhancementof VACUUM FREEZE.<br /> If we want to add the other status not related to visibility into visibility map in
thefuture, it would be worth to consider.<br /><br /> Regards,<br /><br /> --<br /> Masahiko Sawada<br /><br /><br />--
<br/>Regards,<br /><br />--<br />Masahiko Sawada<br />