Re: [HACKERS] Re: PD_ALL_VISIBLE flag was incorrectly set happend during repeatable vacuum

On Mon, Feb 28, 2011 at 10:32 PM, Greg Stark <gsstark(at)mit(dot)edu> wrote:
> On Tue, Mar 1, 2011 at 1:43 AM, David Christensen <david(at)endpoint(dot)com> wrote:
>> Was this cluster upgraded to 8.4.4 from 8.4.0?  It sounds to me like a known bug in 8.4.0 which was fixed by this commit:
>>
>
> The reproduction script described was running vacuum repeatedly. A
> single vacuum run out to be sufficient to clean up the problem if it
> was left-over.
>
> I wonder if it would help to write a regression test that runs 100 or
> so vacuums and see if the bulid farm turns up any examples of this
> behaviour.

One other thing to keep in mind here is that the warning message we've
chosen can be a bit misleading. The warning is:

WARNING: PD_ALL_VISIBLE flag was incorrectly set in relation "test" page 1

...which implies that the state of the tuples is correct, and that the
page-level bit is wrong in comparison. But I recently saw a case
where the infomask got clobbered, resulting in this warning. The page
level bit was correct, at least relative to the intended page
contents; it was the a tuple on the page that was screwed up. It
might have been better to pick a more neutral phrasing, like "page is
marked all-visible but some tuples are not visible".

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company