Re: Should we remove vacuum_defer_cleanup_age?

> On 24 Mar 2023, at 21:27, Andres Freund <andres@anarazel.de> wrote:
> On 2023-03-23 10:18:35 +0100, Daniel Gustafsson wrote:
>>> On 22 Mar 2023, at 18:00, Andres Freund <andres@anarazel.de> wrote:
>> 
>>> It wasn't actually that much work to write a patch to remove
>>> vacuum_defer_cleanup_age, see the attached.
>> 
>> -    and <xref linkend="guc-vacuum-defer-cleanup-age"/> provide protection against
>> +    provides protection against
>>     relevant rows being removed by vacuum, but the former provides no
>>     protection during any time period when the standby is not connected,
>>     and the latter often needs to be set to a high value to provide adequate
>> 
>> Isn't "the latter" in the kept part of the sentence referring to the guc we're
>> removing here?
> 
> You're right. That paragraph generally seems a bit off. In HEAD:
> 
> ...
> 
> Replication slots alone don't prevent row removal, that requires
> hot_standby_feedback to be used as well.
> 
> A minimal rephrasing would be:
>   <para>
>    Similarly, <xref linkend="guc-hot-standby-feedback"/> on its own, without
>    also using a replication slot, provides protection against relevant rows
>    being removed by vacuum, but provides no protection during any time period
>    when the standby is not connected.  Replication slots overcome these
>    disadvantages.
>   </para>

+1, that's definitely an improvement.

--
Daniel Gustafsson