Re: Proposal: Multiversion page api (inplace upgrade)

Zdenek Kotala <Zdenek.Kotala@Sun.COM> writes:
> It does not solve problems for example with TOAST tables. If chunks does not fit 
> on a new page layout one of the chunk tuple have to be moved to free page. It 
> means you get a lot of pages with ~2kB of free unused space. And if max chunk 
> size is different between version you got another problem as well.

> There is also idea to change compression algorithm for 8.4 (or offer more 
> varinats). It also mean that you need to understand old algorithm in a new 
> version or you need to repack everything on old version.

I don't have any problem at all with the idea that in-place update isn't
going to support arbitrary changes of parameters, such as modifying the
toast chunk size.  In particular anything that is locked down by
pg_control isn't a problem.
        regards, tom lane