Re: HOT patch - version 15

"Heikki Linnakangas" <heikki@enterprisedb.com> writes:
> Tom Lane wrote:
>> Then you don't remember far enough --- either the HeapTupleHeader change
>> or the varvarlena change would be enough to prevent that.  For that
>> matter, the pd_flags header field that the patch is already relying on
>> is new for 8.3.

> Yeah, those changes will need to be dealt with in the conversion. But
> none of the changes this far have increased the on-disk size. Adding a
> new field to page header means that in some corner cases it might not be
> possible to convert a page from old format to the new one because the
> data no longer fits.

Counting on my fingers, it seems that the 4-byte savings in
HeapTupleHeader size would guarantee that adding 4 bytes to the page
header wouldn't kill you.

            regards, tom lane