See conference video - http://www.lucidimagination.com/devzone/events/conferences/ApacheLuceneEurocon2011
Trovit is a global classified advertising service covering real estate, jobs and more in 27 countries worldwide. Until recently, our distributed Lucene/Solr search indexes used a customized Data Import Handler to draw data out of MySQL, but they no longer adequately handle our volumes with acceptable performance. We have moved Lucene/Solr indexes using MapReduce and came up with a new way to build indexes which is into production since months ago. Here at Trovit, we deal with many countries and different business categories, each with its own index -- and not all of them have similar size or structure.