As an academic library, we have lots of records with URLs in them. Many of these URLs point to a relatively small number of hosts (either local repositories or purchased commercial resources). Regularly one of these hosts decides to change it's host name or URL somewhat and it would be very convenient to update all records in a single operation using a regexp. For example, all records pointing to http://somepublisher.com/ might have to be redirected through a local proxy using a regexp such as: s|^http://somepublisher.com/|http://localproxy.example.net/login?url=http://somepublisher.com/| The choice between the current substitution and regexp would be made by a drop-box selection. The default would be the current behaviour. Because regexps are inherently more complex than substitutions, previewing the changes would be view important. Ideally preview would be done using AJAX to show the first 5-20 regexp matches immediately under the input field, probably showing a record identifier, original field and new field. My implementation plan would be to do all the regexp work in the perl layer, since I believe that database regexp implementations are fairly divergent. I'm open to suggestions as to which if the several kinds of perl-supported regexps get used. [If I'm not explaining this well, I can mock up a screenshot]
We do have a batch record modification tool now that supports changing 856$u using regex.