London Lucene/Solr Usergroup – Search Relevancy & Hacking Lucene with Doug Turnbull

Last week Doug Turnbull of US-based Open Source Connections visited the UK and spoke at our Meetup. His first talk was on Search Relevancy, an area that we often deal with at Flax: how to tune a search engine to give results that our clients deem relevant, without affecting the results for other queries. Using a client project as an example, Doug talked about how he created a tool to record relevance judgements for a set of queries (or a ‘case’). The underlying Solr search engine could then be adjusted and the tool re-runs the queries to show any change in the position of the scored results. Slides and video of the talk are available – thanks to our hosts SkillsMatter for these.

The tool, Quepid, is a great way to allow non-developers to score search results – in most cases we have seen, if this kind of testing is done at all it is recorded using spreadsheets. The tests then need to be re-run manually and scores updated, which can result in the tuning process taking far too long. This whole area is in need of some rigor and best practise, and to that end Doug is writing a book on Relevant Search which we’re very much looking forward to.

Doug’s second talk was on Hacking Lucene for custom search results, during which he dissected how Lucene queries actually work and how custom scoring algorithms can be used to change search ranking. Although highly technical in parts – and as Doug said, one of the hardest ways to write Lucene code to influence ranking and thus relevance – it was a great window on Lucene’s low level behaviour. Again, slides and video are available.

Thanks to all who came and especially Doug for coming so far to present his talks!

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