In the previous post, I talked about book and card catalogs, and how they existed as a heading layer over the bibliographic description representing library holdings. In this post, I will talk about what changed when that same data was stored in database management systems and delivered to users on a computer screen.
Taking a very simple example, in the card catalog a single library holding with author, title and one subject becomes three separate entries, one for each heading. These are filed alphabetically in their respective places in the catalog.
In this sense, the catalog is composed of cards for headings that have attached to them the related bibliographic description. Most items in the library are represented more than once in the library catalog. The catalog is a catalog of headings.
In most computer-based catalogs, the relationship between headings and bibliographic data is reversed: the record with bibliographic and heading data, is stored once; access points, analogous to the headings of the card catalog, are extracted to indexes that all point to the single record.
This in itself could be just a minor change in the mechanism of the catalog, but in fact it turns out to be more than that.
First, the indexes of the database system are not visible to the user. This is the opposite of the card catalog where the entry points were what the user saw and navigated through. Those entry points, at their best, served as a knowledge organization system that gave the user a context for the headings. Those headings suggest topics to users once the user finds a starting point in the catalog.
When this system works well for the user, she has some understanding of where she was in the virtual library that the catalog created. This context could be a subject area or it could be a bibliographic context such as the editions of a work.
Most, if not all, online catalogs do not present the catalog as a linear, alphabetically ordered list of headings. Database management technology encourages the use of searching rather than linear browsing. Even if one searches in headings as a left-anchored string of characters a search results in a retrieved set of matching entries, not a point in an alphabetical list. There is no way to navigate to nearby entries. The bibliographic data is therefore not provided either in the context or the order of the catalog. After a search on "cat breeds" the user sees a screen-full of bibliographic records but lacking in context because most default displays do not show the user the headings or text that caused the item to be retrieved.
Although each of these items has a subject heading containing the words "Cat breeds" the order of the entries is not the subject order. The subject headings in the first few records read, in order:
- Cat breed
- Cat breeds
- Cat breeds - History
- Cat breeds - Handbooks, manuals, etc.
- Cat breeds
- Cat breeds - Thailand
- Cat breeds
If if the catalog uses a visible and logical order, like alphabetical by author and title, or most recent by date, there is no way from the displayed list for the user to get the sense of "where am I?" that was provided by the catalog of headings.
In the early 1980's, when I was working on the University of California's first online catalog, the catalogers immediately noted this as a problem. They would have wanted the retrieved set to be displayed as:
(Note how much this resembles the book catalog shown in Part I.) At the time, and perhaps still today, there were technical barriers to such a display, mainly because of limitations on the sorting of large retrieved sets. (Large, at that time, was anything over a few hundred items.) Another issue was that any bibliographic record could be retrieved more than once in a single retrieved set, and presenting the records more than once in the display, given the database design, would be tricky. I don't know if starting afresh today some of these features would be easier to produce, but the pattern of search and display seems not to have progressed greatly from those first catalogs.
In addition, it is in any case questionable whether a set of bibliographic items retrieved from a database on some query would reproduce the presumably coherent context of the catalog. This is especially true because of the third major difference between the card catalog and the computer catalog: the ability to search on individual words in the bibliographic record rather than being limited to seeking on full left-anchored headings. The move to keyword searching was both a boon and a bane because it was a major factor in the loss of context in the library catalog.
Keyword searching will be the main topic of Part III of this series.