Nowadays it’s relatively easy to find a base technology to build a search subsystem. From another side, the real challenge is to constantly improve the quality of such systems.  In the talk I will tell about our experience of building lean ranking infrastructure, that could be used with data-driven approach in product development. With slides  we walk through the process of scaling out the search system from a couple to 13 countries around the world, but with still decent level of flexibility,  that allows to perform a/b testing on different levels of the system.