When architecting Google Search Appliance implementations, I am often asked if additional metadata needs to be loaded into the GSA for the project to be successful. The client is usually considering the cost and benefit of manually or automatically tagging additional metadata for every document.
I typically address this question by pointing out precisely how metadata is used by the Google Search Appliance. If the additional metadata is not needed for one of the reasons listed below, it is not needed. Metadata is not like chocolate – more is not always better.
Why do I need metadata?
- Search: Metadata is included as part of the searchable text of an item in the GSA. If the user searches for a word or phase or number that appears in the metadata, it can cause that item to be returned in the search results. Metadata is not included as part of the title or snippet, so it provides a way to make certain text searchable without necessarily showing up in the title or snippet.
- Display: Metadata can be returned with each search result in the XML output, and can be used when constructing the search results display page. This could include thumbnail URLs, authors, dates, price, description, etc. Other than the Title, URL and Snippet, anything else shown on the search results page usually comes from metadata.
- Filtering: Metadata can be used to filter or restrict search results (i.e. only show results where color=blue or category=marketing). Metadata filtering is the foundation of Dynamic Navigation, which is an intuitive way to filter the search results and help users narrow down a large set of results. Metadata filters can also be used behind-the-scene by a search application to limit the search results for certain audiences or types of users (i.e. Show only items published in Japan for the Japaneese audience. Show only items that are “On Sale” when visiting the discount site).
- Biasing: Metadata can be used to construct biasing rules to modify the natural relevancy ranking of results (i.e. Give a stronger bias to any item ranked as “5 stars”. Give weaker bias to any item ranked as “1 or 2 stars”).
- Sorting: New in GSA 7.2, you can sort the search results by one metadata value (i.e. sort by price, name, etc.). You can sort in ascending or descending order, and using either alphabetical or numerical comparison. If you need to sort by more than one metadata at a time, you must load a compound value (i.e. lastname + ‘, ‘ + firstname) into an additional metadata field.