Re: Replication Documentation - Mailing list pgsql-hackers

Markus Schiltknecht wrote:
> Hi,
>
> Andrew Hammond wrote:
>   > I can see value in documenting what replication systems are known to
> > work (for some definition of work) with a given release in the
> > documentation for that release. Five years down the road when I'm
> > trying to implement replication for a client who's somehow locked into
> > postgres 8.2 (for whatever reason), it would be very helpful to know
> > that slony1.2 is an option. I don't know if this is sufficient
> > justification.
>
> Please keep in mind, that most replication solutions (that I know of)
> are quite independent from the PostgreSQL version used. Thus,
> documenting which version of PostgreSQL can be used with which version
> of a replication system should better be covered in the documentation of
> the replication system.

I would agree to this with the caveat that there needs to be something
in the postgres documentation that points people to the various
replication systems available.

> Otherwise you would have to update the
> PostgreSQL documentation for new releases of your favorite replication
> system - which seems to lead to confusion.

Yeah, updating the docs based on other software releases would suck.
How about "what works with a given release at the time of the release"?
Perhaps this could be limited to a pointer to the docs for such
replication systems, and maybe a very brief description (based on
Chris' taxonomy)?

> > Including a separate page on the history of postgres replication to
> > date also makes some sense, at least to me. It should be relatively
> > easy to maintain.
>
> I agree that having such a 'replication guide for users of PostgreSQL'
> is a good thing to have. But I think not much of that should be part of
> the official PostgreSQL documentation - mainly because the replication
> solutions are not part of PostgreSQL.

Arguably, neither are most of the procedural languages in the Server
Programming section of the documentation, and yet they're included. I
agree that it's improtant to keep the documentation from getting
cluttered up with stuff that's "not part of PostgreSQL". However, I
think the very fact so many people assume that there's no replication
for PostgreSQL simply because it's not mentioned in the documentation
shows that for many people replication is precieved as "part of" the
dbms. Even a single page in the documentation wich consists of
something along the lines of the following would help these folks find
what they're looking for.

"There are a number of different approaches to solving the problem of
replication, each with strengths and weaknesses. As a result, there are
a number of different replication solutions available for PostgreSQL.
To find out more, please refer to the website."