The well established measures of recall and precision are becoming increasingly relevant in web-scale discovery systems. Given the way that most people search, which is by using the simple keyword box that searches all text anywhere in the record, web-scale discovery systems will lead to increasingly large recall as we provide access to more linked items. Using the environment of academic libraries, this chapter will explore the following questions: Do we need to be careful about the sheer volume of items to which we can provide access via web-scale discovery systems? Do we want these systems to become another Google, where precision of results is not always as accurate as we would like? Are we too obsessed with the notion of providing access to everything at the expense of the quality of the results?

Introduction – the promise of the one search

‘The Library with a Thousand Databases’ was the amazingly evocative title of a talk given by Matthew Reidsma as part of NISO's Virtual Conference on Web-Scale Discovery in 2013 (Reidsma, 2013). Drawing on Joseph Campbell's work on myth, The Hero with a Thousand Faces (Campbell, 1968), Reidsma drew a parallel between Campbell's ‘hero's journey’, where the aspiring hero ventures from the normal world (use of Google) to the special realm (use of specialized databases), and the experiences first time users face as they start a piece of academic research. A similar idea can be seen in the series of videos The Adventures of Sir Learnsalot, where academic research is depicted as a hero's journey (Tolly, 2013). The use of a library web-scale discovery system, Summon, was then proposed by Reidsma as a partial solution to keep users in the ‘normal world’, at least as much as possible. This is an interesting analogy, though I would argue that the challenge a first time user faces when starting an academic research project goes beyond just using databases, but there is no doubt that web-scale discovery does make things easier from the point of view of searching.