Re: 16-bit page checksums for 9.2

On Wed, Feb 29, 2012 at 2:33 PM, Heikki Linnakangas
<heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
> On 29.02.2012 21:30, Robert Haas wrote:
>>
>> On Wed, Feb 29, 2012 at 2:18 PM, Alvaro Herrera
>> <alvherre(at)commandprompt(dot)com>  wrote:
>>>
>>> Note that if we want such an utility to walk and transform pages, we
>>> probably need a marker in the catalogs somewhere so that pg_upgrade can
>>> make sure that it was done in all candidate tables -- which is something
>>> that we should get in 9.2 so that it can be used in 9.3.  Such a marker
>>> would also allow us get rid of HEAP_MOVED_IN and HEAP_MOVED_OUT.
>>
>>
>> Getting rid of HEAP_MOVED_IN and HEAP_MOVED_OUT would be really nice,
>> but I don't see why we need to squeeze anything into 9.2 for any of
>> this.  pg_upgrade can certainly handle the addition of a new pg_class
>> column, and can arrange for in-place upgrades from pre-9.3 versions to
>> 9.3 to set the flag to the appropriate value.
>
> The utility would run in the old cluster before upgrading, so the the flag
> would have to be present in the old version. pg_upgrade would check that the
> flag is set, refusing to upgrade if it isn't, with an error like "please run
> pre-upgrade utility first".

I find that a pretty unappealing design; it seems to me it'd be much
easier to make the new cluster cope with everything.

--
Robert Haas
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