Wikipedia is both big and famous. Thus, any changes made to Wikipedia are going to affect many people. Moreover, something such as search is used frequently, by people around the world, and in many different languages. So, when the decision was made to change how Wikipedia implements its search system, this meant a lot of thought, planning, testing, and then deploying. In this talk, Nik Everett describes this process, and how Wikipedia switched over to using ElasticSearch without too many problems.