[WEB4LIB] Physical vs. Virual union catalogues

[Roy Tennant]

To my way of thinking, virtual union catalogs are what you do when 
you can't do a physical union catalog. Virtual union catalogs have a 
set of problems that are more difficult to solve than with actual 
union catalogs. For example, de-duping (merging records that are for 
the same item).

If you go search some large virtual union catalogs (for example, 
http://www.aclin.org/ or http://www.mnlink.org/) for an item you 
should quickly see what I mean. Multiple records come back for the 
same book, since records from different libraries are not merged. 
Merging records on the fly can be considerably more difficult than 
merging them in a batch-load operation -- particularly since there is 
no time to iron out problems that cause near-duplicate records not to 
merge. This alone is a serious enough issue to my way of thinking to 
make virtual union catalogs a *last* resort.

But for an actual study on this issue, I don't think you can do 
better than an article by my colleague Karen Coyle, that ran recently 
in D-Lib Magazine: "The Virtual Union Catalog: A Comparative Study" 
(http://www.dlib.org/dlib/march00/coyle/03coyle.html). She found that 
VUCs came up seriously short (in a nutshell).
Roy

At 10:04 PM -0700 5/9/01, George Zachos wrote:
>I am doing research on  physical vs. virtual union library catalogues. I am
>especially interested on the future prospects of both of them.
>
>What is your opinion on this matter?
>
>Any recent work on this subject is wellcome.
>
>Thank you in advance!!!
>
>George
>
>George Zachos, M.Sc., Ph.D.
>University Librarian
>University of Ioannina
>Central Library
>P.O.Box 1186
>GR-45110 Ioannina
>Greece
>Tel.: +30-651-97138 Fax:+30-651-97003
>gzaxos at cc.uoi.gr
>http://www.lib.uoi.gr