Re: Reviewing freeze map code

On Sat, Jun 4, 2016 at 12:59 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Fri, Jun 3, 2016 at 11:21 AM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>>> Can you submit that part as a separate patch?
>>
>> Attached.
>
> Thanks, committed.
>
>>>> I'm address the review comment of 7087166 commit, and will post the patch.
>>>
>>> When?
>>
>> On Saturday.
>
> Great.  Will that address everything for this open item, then?
>

Attached patch for commit 7087166 on another mail.
I think that only the test tool for visibility map is remaining and
under the discussion.
Even if we have verification tool or function for visibility map, we
cannot repair the contents of visibility map if we turned out that
contents of visibility map is something wrong.
So I think we should have the way that re-generates the visibility map.
For this purpose, doing vacuum while ignoring visibility map by a new
option or new function is one idea.
But IMHO, it's not good idea to allow a function to do vacuum, and
expanding the VACUUM syntax might be somewhat overkill.

So other idea is to have GUC parameter, vacuum_even_frozen_page for example.
If this parameter is set true (false by default), we do vacuum whole
table forcibly and re-generate visibility map.
The advantage of this idea is that we don't necessary to expand VACUUM
syntax and relatively easily can remove this parameter if it's not
necessary anymore.

Thought?

Regards,

--
Masahiko Sawada