Friday, August 5, 2011

Re: XML vs. MARC

Posting to RDA-L

On 04/08/2011 17:32, Kevin M Randall wrote:
<snip>
James Weinheimer wrote:
I keep repeating that ISO2709 is used for *transfer* of records and not storage.
While you keep repeating it, that doesn't necessarily make it so. As I have written several times now, the Ex Libris Voyager system most certainly DOES store records essentially in the ISO2709 format. Whether or not that is a good thing, I'm not going to comment on. But I just want to point out that what you are asserting is most definitely untrue.
</snip>
Yes, you mentioned that before and I went on vacation. If Voyager stores everything in ISO2709 format, that is fine, but it also definitely has relational database structures using the Oracle database, which is highly advanced, see http://www.exlibrisgroup.com/category/TechnicalStrategicPartners. I remember when I was still at Princeton and we were implementing Voyager, we all had to learn the basics of relational databases. In Voyager, I don't know how the Oracle database is used with the ISO2709 format. Not seeing the structures, I can only guess that it is kind of like in Koha, where it uses the zebra indexing while it retains the MARC record as a whole in a single database cell, except Koha uses MARCXML, which gets rid of a lot of headaches. When you update a record, I think you are actual updating the MARCXML record which is then propagated into the zebra indexes, but I am not sure about this.

I don't know how some things could work with live ISO2709, especially updates in an authorities module that affects hundreds or thousands of records. To keep the ISO2709 valid you have to update everything within the leader and directory structures as well, which harkens back to the nightmares of the old "global changes" that had a tendency to blow up. But if this is done successfully in Voyager, I would certainly like to find out how. And more importantly, why.

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