Re: pgsql: Allow vacuums to report oldestxmin

On Wed, Mar 29, 2017 at 1:32 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> On Tue, Mar 28, 2017 at 1:06 AM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>> On Sun, Mar 26, 2017 at 2:26 AM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>>> On Sun, Mar 26, 2017 at 1:37 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
>>>> On Mon, Mar 6, 2017 at 9:37 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>>>>> On Fri, Mar 3, 2017 at 10:50 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>>>>>> Allow vacuums to report oldestxmin
>>>>>>
>>>>>> Allow VACUUM and Autovacuum to report the oldestxmin value they
>>>>>> used while cleaning tables, helping to make better sense out of
>>>>>> the other statistics we report in various cases.
>>>>>>
>>>>>> Branch
>>>>>> ------
>>>>>> master
>>>>>>
>>>>>> Details
>>>>>> -------
>>>>>> http://git.postgresql.org/pg/commitdiff/9eb344faf54a849898d9be012ddfa8204cfeb57c
>>>>>>
>>>>>> Modified Files
>>>>>> --------------
>>>>>> src/backend/commands/vacuumlazy.c | 9 +++++----
>>>>>> 1 file changed, 5 insertions(+), 4 deletions(-)
>>>>>>
>>>>>>
>>>>>
>>>>> Should we change the example in vacuum.sgml file as well? Attached patch.
>>>>
>>>> "tuples" in the above should be "row versions"?
>>>> We should review not only this line but also all the lines in the example
>>>> of VERBOSE output, I think.
>>>
>>> Right. These verbose log messages are out of date. I ran
>>> VACUUM(VERBOSE, ANALYZE) with same scenario as current example as
>>> possible. Attached patch updates verbose log messages.
>>>
>>>
>>
>> Surprisingly the changes "tuples" -> "row versions" in vacuumlazy.c is
>> introduced by commit feb4f44d296b88b7f0723f4a4f3945a371276e0b in 2003.
>
> This is the evidence that no one cares about the details of VACUUM VERBOSE
> output example. So I'm tempted to simplify the example (please see the
> attached patch) instead of keeping updating the example.

Yes. I agree.

>
>> If this patch is applied, it should back-patch to all supported
>> branches.
>
> Not sure if it's worth back-patching that.
>
> Regards,
>
> --
> Fujii Masao

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center