== Blockers
[] All current eventlogging bugs are resolved and data is confirmed by Tilman (see {T158172}).
[] Deployment must not happen prior to Wednesday, August 2
== Plan (YMMV):
[] Reset the instrumentation sampling rate to 0.001 for all wikis, i.e. revert {d5c4bd72}.
[] Deployment must happen in few stages (3 or more) in order to make rollback easier – if we start overloading the edge caches (and origin servers potentially), say.
* Deploy to a chunk of 50 wikis and assess the impact on Page Previews, RESTBase, and Varnish performance, if any.
* https://grafana.wikimedia.org/dashboard/db/reading-web-page-previews
* https://grafana.wikimedia.org/dashboard/db/varnish-caching?var-cluster=text&var-site=All
* If there's no significant impact, then increase the chunk size to 100/150/200.
[] The Ops and Services teams are notified after each deploy.
[] We pause for a day (at least) between deploys so that each team has a chance to observe the effect of increased load.
= Current status
[] A patch has been uploaded https://gerrit.wikimedia.org/r/#/c/351287/ and is blocked pending a discussion.