Re: Reviewing freeze map code

On Mon, Jun 6, 2016 at 6:34 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Mon, Jun 6, 2016 at 5:11 AM, Michael Paquier
> <michael.paquier@gmail.com> wrote:
>>> Attached is a sample patch that controls full page vacuum by new GUC parameter.
>>
>> Don't we want a reloption for that? Just wondering...
>
> Why?  Just for consistency?  I think the bigger question here is
> whether we need to do anything at all.  It's true that, without some
> new option, we'll lose the ability to forcibly vacuum every page in
> the relation, even if all-frozen.  But there's not much use case for
> that in the first place.  It will be potentially helpful if it turns
> out that we have a bug that sets the all-frozen bit on pages that are
> not, in fact, all-frozen.  Otherwise, what's the use?
>

I cannot agree with using this parameter as a reloption.
We set it true only when the serious bug is discovered and we want to
re-generate the visibility maps of specific tables.
I thought that control by GUC parameter would be convenient rather
than adding the new option.

Regards,

--
Masahiko Sawada