Re: Freeze avoidance of very large table.

On Fri, Nov 13, 2015 at 4:48 AM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
wrote:
>
>
> Thank you for reviewing the patch.
>
> I changed the patch so that the visibility map become the page info
> map, in source code and documentation.
>

One thing to notice is that this almost doubles the patch size which
might makes it slightly difficult to review, but on the other hand if
no-body opposes for such a change, this seems to be the right direction.

> And fixed review comments I received.
> Attached v22 patch.
>
> > I think both the above cases could happen for frozen state
> > as well, unless you think otherwise, we need similar handling
> > for frozen bit.
>
> It's not happen the situation where is all-frozen and not all-visible,
> and the bits of visibility map are cleared at the same time, page
> flags are as well.
> So I think it's enough to handle only all-visible situation. Am I
>
> missing something?
>

No, I think you are right as information for both is cleared together
and all-visible is superset of all-frozen (means if all-frozen is set,
then all-visible must be set), so it is sufficient to check visibility
info in above situation, but I feel we can update the comment to
indicate the same and add an Assert to ensure if all-frozen is set
all-visibile must be set.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com