Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!prowest!pan
From: pan@propress.com (Philip A. Naecker)
Newsgroups: comp.databases
Subject: Re: Any Existing Replicating Databases?
Message-ID: <3043@propress.com>
Date: 22 Feb 90 17:22:36 GMT
References: <275@gollum.UUCP>
Organization: Professional Press West Coast Offices, Pasadena, CA
Lines: 35

In article <275@gollum.UUCP>, wasmith@gollum.UUCP (Wayne A. Smith) writes:
> Are there any existing databases (products or research
> prototypes) that feature replication? That is, are there
> any databases that allow two copies on a network to be
> maintained strongly consistent with each other? When one
> is updated, that change is propogated to its copy(ies).
>

Digital sells a product called the VAX Data Distributor.  VDD works with Rdb to
distribute data to and from Rdb databases.  The distribution can be either from
a central database (where the updates take place) to one or more remote
databases, or the other way 'round (as in rollup of data from branch offices,
for example.

VDD is quite smart about how it updates the remote databases, in that it can
either send the entire database or relation, or just those records that have
been updated.  It also can be set up to send updates with various periodicity
(or immediately), such as "send this out every Tuesday night".

There are some limitations, but overall VDD solves several of the problems of
distributing data to or from multiple sites.

If you need more info, get the VDD Software Product Description from DEC.




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Philip A. Naecker                            Consulting Software Engineer
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FAX:      +1 818 577 0073                    Also: Technology Editor
                                                   DEC Professional Magazine
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