| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> |
| Cc: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Masao Fujii <masao(dot)fujii(at)gmail(dot)com>, Álvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Petr Jelinek <petr(at)2ndquadrant(dot)com>, Greg S <stark(at)mit(dot)edu>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Freeze avoidance of very large table. |
| Date: | 2015-12-21 14:54:07 |
| Message-ID: | CA+TgmoY9tDEc9WphMP2qw-MnpqaB9Cuye5RRzMQxkVR-3tzFHA@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Mon, Dec 21, 2015 at 3:27 AM, Kyotaro HORIGUCHI
<horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> Hello,
>
> At Fri, 18 Dec 2015 12:09:43 -0500, Robert Haas <robertmhaas(at)gmail(dot)com> wrote in <CA+TgmoZCCFwgKL0PmSi=htfZ2aCOZPoTPD73ecvSA9rhXa0zUw(at)mail(dot)gmail(dot)com>
>> On Thu, Dec 17, 2015 at 1:17 AM, Michael Paquier
>> <michael(dot)paquier(at)gmail(dot)com> wrote:
>> > I am not really getting the meaning of this sentence. Shouldn't this
>> > be reworded something like:
>> > "Freezing occurs on the whole table once all pages of this relation require it."
>>
>> That statement isn't remotely true, and I don't think this patch
>> changes that. Freezing occurs on the whole table once relfrozenxid is
>> old enough that we think there might be at least one page in the table
>> that requires it.
>
> I doubt I can explain this accurately, but I took the original
> phrase as that if and only if all pages of the table are marked
> as "requires freezing" by accident, all pages are frozen. It's
> quite obvious but it is what I think "happen to require freezing"
> means. Does this make sense?
>
> The phrase might not be necessary if this is correct.
Maybe you are trying to say something like "only those pages which
require freezing are frozen?".
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Simon Riggs | 2015-12-21 14:54:22 | Avoiding pin scan during btree vacuum |
| Previous Message | Victor Wagner | 2015-12-21 14:50:13 | Re: Patch: Implement failover on libpq connect level. |