Because of keyword inheritances, a search can result in many more hits than the user wants to read. Horizon uses one of six filters to narrow the records that are hits. The user can then click on Related Subjects to view related titles that did not pass the filter.
Horizon uses these filters:
• | Hierarc2. Selects the highest level record, or the one that is linked the furthest back, that meets the conditions of the search string. |
• | HitFilt. Selects only the records that meet the search string and at least one keyword directly. |
• | MinFil. Selects the record with the lowest bib record number that meets the conditions of the search string. |
• | NoFilt. Selects all records that meet the conditions of the search string. |
• | PrHier2. Selects the highest level record in a subtree with priority consideration. |
• | PrHitF. Selects only the records that meet the search string and at least one keyword directly, with priority consideration. |
Horizon comes with one of these filters set up as a default for each link class. The default filter for all hierarchical type links (hierarchical, series, and supplement classes) is “hierarc2.” The default filter for all other links is “hitfilt.” You can override the default filters in the search_link_class_filter view. If this view is empty, Horizon is using the defaults as described.
Some bib records may be linked together using different classes. Horizon considers each class in a linked bib structure for hits in PAC or staff searching. This is called “priority filtering.”
For example, this structure contains a main record linked to a multivolume work using the hierarchical link class. Each title in the multivolume work is linked to a German translation using the Translation class. Both the Hierarchical link class and Translation link class are considered for hits in searches against your database:
Priority filters narrow search results by limiting what classes are considered for hits. A priority filter lets you order the classes you want considered for hits. When one class yields hits, Horizon stops searching the others for hits. This is called “priority consideration.”
This table shows examples of searches using standard filters and priority filters on the previous linked bib structure (the prefix “pr” denotes a priority filter):
Keyword Search String |
Link Classes |
Filter |
Priority of Classes |
Resulting Hits |
“Drama” |
Hierarchical Translations |
Hierarc2 hitfilt |
NA |
W.Shakespeare |
“Drama” |
Hierarchical Translations |
prhierarc2 prhitfilt |
1. Hierarchical 2. Translations |
Henry IV, Henry VIII, Richard II |
“W.Shakespeare” |
Hierarchical Translations |
hierarch2 hitfilt |
Hierarchical |
NA |
“W.Shakespeare and drama” |
Hierarchical Translations |
prhierarchical prhitfilt |
1. Hierarchical 2. Translations |
W.Shakespeare NA |
Each of these search strings deals with the Hierarchical and Translations link classes, because they are the two classes in the linked bib structure. The first search uses the default filters for these classes (hierarc2 and hitfilt). Because these are standard filters, the priority each class receives is not applicable. The hierarchical filter yields “W. Shakespeare” as a resulting hit, and the “hitfilter” yields the English version of the plays.
The second search uses the priority filters. The translations link class is prioritized before the Hierarchical class. The prhitfilter yields the English plays as resulting hits, and so the second filter is not considered.
You use the same view to assign priority or non-priority filters.
To assign link filters
View: search_link_class_filter
➢ | In these fields, do the following: |
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