Re: Distributed Database Issues

hts_at_sasdata.no (Haakon T. Soenderland) wrote:
>
> Hi all,
>
> I'm sitting here looking at the white-paper on Distributed Database
> Technology and Symmetric Replication from the Oracle WWW-site
> (http://www.oracle.com/info/products/entserver72/ddtsr.html).
>
> I'm wondering about some of the statements Oracle makes in this paper
> and would be interested in your comments on them.
>
> In the section on "Synchronous Distributed Technology" they say:
>
> "Synchronous technology ensures application integrity and minimizes
> complexity, but can have poorer response time performance and less
> availability if the systems and networks involved are unreliable
> and slow."
>
> and in the section on "Asynchronous Distributed Technology" they say:
>
> "Asynchronous technology maximizes availability and response time
> performance, but can be more complex and requires careful planning
> and design to enure application integrity."
>
> I'm reading (or interpreting) this (and the rest of the document)
> to mean that Oracle thinks that using PL/SQL, triggers and procedures
> is easier to set up and manage than snapshots.
>
> I would think that setting up a synchronous distribution environment
> would be just as complex as setting up an asynchronous one.
>
> More important, I would think that maintenance and expansion of such
> an environment would be easier using asynchronous replication (snapshots)
> than using synchronous distribution (i.e PL/SQL, triggers and procedures).
> One should think that adding one more site with synchronous
> distribution would involve writing or re-writing lots of
> PL/SQL, while adding another snapshot site would be easier (since its
> deklarative).
>
> Having little experience with this technology, I might be dead wrong.
> However, it seems to me that if one is using replication, it would
> be easier to set up and manage snapshots then writing the replication
> code yourself. I'm most concerned about management and maintenance
> of such an environment. Setting it up migth be difficult, but it is
> an onetime job, whilst one could imagine such a system expanding and
> beeing in operation for years. Thats when it needs to be managable and
> maintainable.
>
> What are your thoughts?
>
> I'm also wondering if anyone can tell me about the underlying technology
> for the "Multiple Master" replication they are talking about. They are
> saying that it uses "Deferred RPC" as the undelying technology, but does
> that mean that you'll have to write these RPC's yourself? Or is there
> a layer "over" this that you use (as with snapshots)?
>
>
> Thanks,
> Haakon
> --
> hts_at_sasdata.no | haakon.soenderland_at_thcave.bbs.no | Haakon T. Soenderland
> Scandinavian Airlines Data Norway A/S
> ---
> "40 skiver og et herpa anlegg, en leilighet som trenger aa spyles. Ingen
> venner og ingen penger, alt jeg har er mine klamme hender.." Jokke '94
> Windows 95: A another first from Microsoft!
> The first OS to be obsolete *before* it was released.
>
Writing PL/SQL code gives you the ability to handle errors that occur rather than waiting for the network or server to come up. With the addition of dynamic SQL in version 7.1 and greater, the database location can be dynamically added into the statement then executed. I am doing this at the moment sending data records to 4 remote sites. I have a team that does this type of developement. If you need more information let me know.

D. Kim Hughes
DRT Systems International
Houston, Tx (713) 868-5537 x312 Received on Mon Aug 14 1995 - 00:00:00 CEST