Greg Stark napsal(a):
> I don't think this really qualifies as "in place upgrade" since it would
> mean creating a whole second copy of all your data. And it's only online
> got read-only queries too.
>
> I think we need a way to upgrade the pages in place and deal with any
> overflow data as exceptional cases or else there's hardly much point in
> the exercise.
It is exceptional case between V3 and V4 and only on heap, because you save in
varlena. But between V4 and V5 we will lost another 4 bytes in a page header ->
page header will be 28 bytes long but tuple size is same.
Try to get raw free space on each page in 8.3 database and you probably see a
lot of pages where free space is 0. My last experience is something about 1-2%
of pages.
Zdenek
