On 2013-05-29 23:01:31 -0400, Robert Haas wrote:
> On Wed, May 29, 2013 at 9:57 AM, Andres Freund <andres@2ndquadrant.com> wrote:
> >> Thought about that, but given that 9.3's visibilitymap_set already will
> >> already FPI heap pages I concluded it wouldn't really be an improvement
> >> since it's only one ||log_heap_page or so there. Not sure what's
> >> better. Will write the patch and see how it goes.
> >
> > Ended up using log_newpage_buffer since reusing visibilitymap_set's
> > record would break the wal format as we currently do not accept an FPI
> > on the heap pages during replay when < 9.3. Forcing to upgrade the
> > client first would be rather unfriendly...
> >
> > That has the disadvantage of logging a full heap page since it doesn't
> > use the hole optimization but this happens really infrequently, so ...
>
> Yeah, I think it's fine. The patch also looks fine, although I think
> the comments could use a bit of tidying. I guess we need to
> back-patch this all the way back to 8.4? It will require some
> adjustments for the older branches.
I think 9.2 is actually far enough and it should apply there. Before
that we only logged the unsetting of all_visible via
heap_(inset|update|delete)'s wal records not the setting as far as I can
tell. So I don't immediately see a danger < 9.2.
Greetings,
Andres Freund
-- Andres Freund http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services
