Karl O. Pinc wrote:
> Hi,
>
> What is the best pg_dump format for long-term database
> archival? That is, what format is most likely to
> be able to be restored into a future PostgreSQL
> cluster.
>
> Mostly, we're interested in dumps done with
> --data-only, and have preferred the
> default (-F c) format. But this form is somewhat more
> opaque than a plain text SQL dump, which is bound
> to be supported forever "out of the box".
> Should we want to restore a 20 year old backup
> nobody's going to want to be messing around with
> decoding a "custom" format dump if it does not
> just load all by itself.
For schema dumps the custom format has advantages IMHO,
mainly because it adds flexibility. When creating text-formatted
dumps, you have to specify options like "--no-owner, ..."
at _dumping_ time, while custom-format dumps allow you to
specify them at _restoration_ time.
For data-dumps this is less relevant, since the amount of
available options is much smaller. But even there, restoring
with "insert-statements" as opposed to "copy from stdin" could
be usefull in some situations.
Anyway, 20 years is a _long_, _long_ time. If you _really_
need to keep your data that long, I'd suggest you create
text-only schema dumps, and text-only data dumps. The postgres
developers are very concerned about backward compatibility in
my experience, but probably _not_ for versions from 20 years ago ;-)
But since the probability of the need to restore your backup
in 6 months is _much_ larger than the one of needing to restore
it in 20 years, I'd create customer-format dumps too.
For the near future, they're the better choice IMHO.
> Is the answer different if we're dumping the
> schema as well as the data?
The above holds true for the schema as well as for the data.
greetings, Florian Pflug