Re: WAL file internals and why a 64 bit will not work on a 32 bit

Thanks.

If I partition my disk differently between the primary and standby
will that be a problem?

Regards
Dhaval

On 5/10/07, Richard Huxton <dev@archonet.com> wrote:
> Dhaval Shah wrote:
> > I do know that WAL files taken from a 64 bit OS will not work on a 32
> > bit OS. However I have to prepare a technical answer to this.
> >
> > That is, questions like - why a WAL file from 64 bit will not work in
> > 32 bit. Also does the WAL file differ for same architecture but
> > different kind of partitions?
>
> The WAL files track on-disk changes. That is, they represent the bytes
> changed in individual blocks. So - both machines will need to have
> *identical* on-disk formats for the WAL transfer to work.
>
> It can be something as small as a configuration option chosen when
> compiling PostgreSQL. For example - you can change between
> floating-point and integer date-times at ./configure time and if you use
> different settings on two identical machines then the WAL files will be
> incompatible.
>
> The obvious incompatibility I'd expect in a 32 to 64-bit changeover
> would be alignment of data fields to 32 or 64-bit boundaries. I've not
> checked, but I'd be surprised if there wasn't some difference there.
>
> --
>    Richard Huxton
>    Archonet Ltd
>


--
Dhaval Shah