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

On Wed, Jan 12, 2011 at 10:46:14AM +0200, Heikki Linnakangas wrote:
> On 12.01.2011 06:21, Fujii Masao wrote:
> >On Sat, Dec 25, 2010 at 2:09 PM, Maxim Boguk<maxim(dot)boguk(at)gmail(dot)com> wrote:
> >>While I trying create reproducible test case for BUG #5798 I
> >>encountered very strange effect on two of my servers (both servers
> >>have same hardware platform/OS (freebsd 7.2) and PostgreSQL 8.4.4).
> >>
> >>Very simple test table created as:
> >>CREATE TABLE test (id integer);
> >>INSERT INTO test select generate_series(0,10000);
> >>
> >>And I trying repeateble vacuum of that table with script:
> >> perl -e "foreach (1..100000) {system \"psql -d test -h -c 'vacuum
> >> test'\";}"
> >>
> >>And once per like an minute (really random intervals can be 5 minutes
> >>without problems can be 3 vacuum in row show same error) I getting
> >>next errors:
> >>WARNING: PD_ALL_VISIBLE flag was incorrectly set in relation "test" page
> >>1
> >>...
> >>WARNING: PD_ALL_VISIBLE flag was incorrectly set in relation "test"
> >>page 30 for all pages of the relation.
>
> Oh, interesting. This is the first time anyone can reliably reproducible
> that. I can't reproduce that on my laptop with that script, though, so
> I'm going to need your help to debug this.
>
> Can you compile PostgreSQL with the attached patch, and rerun the test?
> It will dump the pages with incorrectly set flags to files in /tmp/, and
> adds a bit more detail in the WARNING. Please run the test until you
> get those warnings, and tar up the the created "/tmp/pageimage*" files,
> and post them along with the warning generated.
>
> We'll likely need to go back and forth a few times with various
> debugging patches until we get to the heart of this..

Anything new on this? I'm seeing at on one of my clients production boxes.
Also, what is the significance, ie what is the risk or damage potential if
this flag is set incorrectly?

Thanks

-dg

--
David Gould daveg(at)sonic(dot)net
If simplicity worked, the world would be overrun with insects.