Re: Freeze avoidance of very large table.

On Wed, Jan 13, 2016 at 12:16 AM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> On Mon, Dec 28, 2015 at 6:38 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>> On Mon, Dec 21, 2015 at 11:54 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> 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?".
>>>
>>
>> I was thinking the same as what Horiguchi-san said.
>> That is, even if relfrozenxid is old enough, freezing on the whole
>> table is not required if the table are marked as "not requires
>> freezing".
>> In other word, only those pages which are marked as "not frozen" are frozen.
>>
>
> The recently changes to HEAD conflicts with freeze map patch, so I've
> updated and attached latest freeze map patch.
> The another patch that enhances the debug log message of visibilitymap
> is attached to previous mail.
> <http://www.postgresql.org/message-id/CAD21AoBScUD4k_QWrYGRmbXVruiekPY=2BY2Fxhqq55a+tzUxg@mail.gmail.com>.
>
> Please review it.
>

Attached updated version patch.
Please review it.

Regards,

--
Masahiko Sawada