Re: Freeze avoidance of very large table.

On Tue, Dec 1, 2015 at 3:04 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> On Mon, Nov 30, 2015 at 9:18 AM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>> On Sun, Nov 29, 2015 at 2:21 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
>>> On Tue, Nov 24, 2015 at 3:13 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>>>>
>>>> Yeah, we need to consider to compute checksum if enabled.
>>>> I've changed the patch, and attached.
>>>> Please review it.
>>>
>>> Thanks for the update. This now conflicts with the updates doesn to
>>> fix pg_upgrade out-of-space issue on Windows. I've fixed (I think) the
>>> conflict in order to do some testing, but I'd like to get an updated
>>> patch from the author in case I did it wrong. I don't want to find
>>> bugs that I just introduced myself.
>>>
>>
>> Thank you for having a look.
>>
>> Attached updated v28 patch.
>> Please review it.
>>
>> Regards,
>
> After running pg_upgrade, if I manually vacuum a table a start getting warnings:
>
> WARNING: page is not marked all-visible (and all-frozen) but
> visibility map bit(s) is set in relation "foo" page 32756
> WARNING: page is not marked all-visible (and all-frozen) but
> visibility map bit(s) is set in relation "foo" page 32756
> WARNING: page is not marked all-visible (and all-frozen) but
> visibility map bit(s) is set in relation "foo" page 32757
> WARNING: page is not marked all-visible (and all-frozen) but
> visibility map bit(s) is set in relation "foo" page 32757
>
> The warnings are right where the blocks would start using the 2nd page
> of the _vm, so I think the problem is there. And looking at the code,
> I think that "cur += SizeOfPageHeaderData;" in the inner loop cannot
> be correct. We can't skip a header in the current (old) block each
> time we reach the end of the new block. The thing we are skipping in
> the current block is half the time not a header, but the data at the
> halfway point through the block.
>

Thank you for reviewing.

You're right, it's not necessary.
Attached latest v29 patch which removes the mention in pg_upgrade documentation.

Regards,

--
Masahiko Sawada