Section 8.2. Search System Anatomy


8.2. Search System Anatomy

On its surface, search seems quite straightforward. Look for the box with the search button, enter and submit your query, and mutter a little prayer while the results load. If your prayers are answered, you'll find some useful results above the fold and can go on with your life.

Of course, there's a lot going on under the hood. A search engine application has indexed content on the site. All of it? Some of it? As a user, you'll probably never know. And what parts of the content? Usually the search engine can find the full text of each document. But a search engine can also index information associated with each documentlike titles, controlled vocabulary terms, and so forthdepending on how it's been configured. And then there's the search interface, your window on the search engine's index. What you type there is looked up in the index; if things go well, results that match your query are returned.

A lot is going on here. There are the guts of the search engine itself; aside from tools for indexing and spidering, there are algorithms for processing your query into something the software can understand, and for ranking those results. There are interfaces, too: ones for entering queries (think simple and advanced search) and others for displaying results (including decisions on what to show for each result, and how to display the entire set of results). Further complicating the picture, there may be variations in query languages (for example, whether or not Boolean operators like AND, OR, and NOT can be used) and query builders (like spell checkers) that can improve upon a query.

Obviously, there's a lot to search that doesn't meet the eye. Additionally, there's your query, which itself usually isn't very straightforward. Where does your query come from? Your mind senses a gap that needs to be filledwith informationbut isn't always sure how to express it. Searching is often iterativenot just because we don't always like the results we retrieve, but often because it takes us a few tries to get the words right for our query. You then interact with a search interface, heading for the simple, Google-like box or, if you're "advanced," grappling with the advanced search interface. And finally, you interact with results, which hopefully help you quickly determine which results are worth clicking through, which to ignore, and whether or not you should go back and try modifying your search. Figure 8-1 shows some of these pathways.

Figure 8-1. The basic anatomy of a search system (image from "In Defense of Search," Semantic Studios, http://www.semanticstudios.com/publications/semantics/search.html)


That's the 50,000-foot view of what's happening in a search system. Most of the technical details can be left to your IT staff; as an information architect, you are more concerned with factors that affect retrieval performance than with the technical guts of a search engine. But as we discuss in the following section, you don't want to leave too much in the hands of IT.




Information Architecture for the World Wide Web
Information Architecture for the World Wide Web: Designing Large-Scale Web Sites
ISBN: 0596527349
EAN: 2147483647
Year: 2006
Pages: 194

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