Re: Re: Is it possible to mirror the db in Postgres?

You probably already thought of this - but - why not just set up a
centralized server and have each office interact to the db via a web
interface. Let your application enforce security (apacheSSL, use db for
user auth) and to prevent two users from editing the same record
simultaneously.

-r

At 06:19 PM 4/20/01 -0700, Nathan Myers wrote:

>On Fri, Apr 20, 2001 at 04:53:43PM -0700, G. Anthony Reina wrote:
> > Nathan Myers wrote:
> >
> > > Does the replication have to be reliable? Are you equipped to
> > > reconcile databases that have got out of sync, when it's not?
> > > Will the different labs ever try to update the same existing
> > > record, or insert conflicting (unique-key) records?
> >
> > (1) Yes, of course. (2) Willing--yes; equipped--dunno. (3) Yes,
> > probably.
>
>Hmm, good luck. Replication, by itself, is not hard, but it's only
>a tiny part of the job. Most of the job is in handling failures
>and conflicts correctly, for some (usually enormous) definition of
>"correctly".
>
> > > Reliable WAN replication is harder. Most of the proprietary database
> > > companies will tell you they can do it, but their customers will tell
> > > you they can't.
> >
> > Joel Burton suggested the rserv utility. I don't know how well it would
> > work over a wide network.
>
>The point about WANs is that things which work nicely in the lab, on a
>LAN, behave very differently when the communication medium is, like the
>Internet, only fitfully reliable. You will tend to have events occurring
>in unexpected order, and communications lost, and queues topping over,
>and conflicting entries in different instances which you must somehow
>reconcile after the fact. Reconciliation by shipping the whole database
>across the WAN is often impractical, particularly when you're trying to
>use it at the same time.
>
>WAN replication is an important part of Zembu's business, and it's hard.
>I would expect the rserv utility (about which I admit I know little) not
>to have been designed for the job.
>
>Nathan Myers
>ncm(at)zembu(dot)com
>
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