Re: WORM and Read Only Tables (v0.1)

On 11/12/2007, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>
> Attach
> ------
>
> Writing tables on one system and then moving that data to other systems
> is fairly common. If we supported read-only tables then you might
> consider how you would publish new versions to people.
>
> For now, we just want to consider how we will upgrade from one release
> to another without needing to unload and reload potentially many
> Terabytes of data. We can't delete the old data until the new data is
> successfully loaded, so we will have a huge temporary storage cost. This
> could go very slowly if we use cheaper storage, plus reloading the data
> means we have to re-freeze it again also.
>
> So we need a way of attaching the old tables to the new database. We
> might call this binary upgrade, or we might be slightly less ambitious
> and talk about just moving the old read-only data. That's all I want to
> do at this stage.
>
> I'm mentioning this here now to see what comes out in debate, and what
> others are planning to work on in this area.
>
>
This sounds like allowing new versions to read old versions file structure,
Probably I guess on a tablespace by table space basis

Another advantage might be to be able to load an old pitr backup in a new
version across major versions. But I'm not sure that would work.

Maybe we need a command to upgrade a tablespace to a new versions file
format?

Need to be careful we don't stunt future progress by fixing file format
much.

Peter Childs