Re: Block-level CRC checks

On Fri, Dec 4, 2009 at 9:48 AM, Alvaro Herrera
<alvherre(at)commandprompt(dot)com> wrote:
> Heikki Linnakangas escribió:
>> Simon Riggs wrote:
>> > On Fri, 2009-12-04 at 09:52 -0300, Alvaro Herrera wrote:
>> >
>> >> BTW with VACUUM FULL removed I assume we're going to get rid of
>> >> HEAP_MOVED_IN and HEAP_MOVED_OFF too, right?
>> >
>> > Much as I would like to see those go, no. VF code should remain for some
>> > time yet, IMHO.
>>
>> I don't think we need to keep VF code otherwise, but I would leave
>> HEAP_MOVED_IN/OFF support alone for now for in-place upgrade. Otherwise
>> we need a pre-upgrade script or something to scrub them off.
>
> CRCs are going to need scrubbing anyway, no?  Oh, but you're assuming
> that CRCs are optional, so not everybody would need that, right?

If we can make not only the validity but also the presence of the CRC
field optional, it will simplify things greatly for in-place upgrade,
I think, because the upgrade won't itself require expanding the page.
Turning on the CRC functionality for a particular table may require
expanding the page, but that's a different problem. :-)

Have we thought about what other things have changed between 8.4 and
8.5 that might cause problems for in-place upgrade?

...Robert