As part of the cross-wiki search results new functionality, we'll need to figure out how to setup the CirrusSearch configuration:

• we probably have to switch configs from per-wiki to per-index, inside mediawiki config
• need to have same global config everywhere
  • this causes problems with the way we deploy new versions (staggered deployments over a period of 3 days)
• need flags to enable after deployment to make sure we don't have missing features
• may not be able to do phased roll out to smaller wikis first (sometimes can, sometimes can't)
• smaller wikis have fewer replicas (e.g., wikt = 2, wp = 6), we'd have to replicate them at big-wiki scale
  • could use up lots more disk (or not)