Re: Challenges preventing us moving to 64 bit transaction id (XID)?

On Thu, Mar 1, 2018 at 11:48 PM Alexander Korotkov <
a(dot)korotkov(at)postgrespro(dot)ru> wrote:

> Hi!
>
> On Fri, Mar 2, 2018 at 1:41 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>
>> On 2018-01-11 01:02:52 +0300, Alexander Korotkov wrote:
>> > As I get from cputube, patchset doesn't compiles again. Please find
>> > revised version attached.
>>
>> It'd be good if you could maintain the patches as commits with some
>> description of why you're doing these changes. It's a bit hard to
>> figure that out sometimes and having to dig through a thread with quite
>> some discussion certainly makes it less likely to be looked at.
>>
>
> Thank you for pointing. In future I'll maintain patches with their
> description.
> BTW, during FOSDEM developer meeting we decided that I should extract
> 64-bit in-memory representation of xids and resubmit it, while 64-bit
> on-disk reprensentation should become a pluggable table access method.
> I didn't manage to do this before current commitfest. Also, the last
> commitfest
> is already too late for such big changes. So, I'm marking this RWF.
>

I am wondering about this point. If there are different access methods,
what does that mean for transactions crossing the 32-bit mark? Is it
possible that supporting 32-bit representations and 64-bit representations
together could cause visibility problems and bugs? Or is that with the
idea that pages would be upgraded on write?

>
> ------
> Alexander Korotkov
> Postgres Professional: http://www.postgrespro.com
> The Russian Postgres Company
>

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