As you may have been aware, we've been working on changing how MediaWiki stores "actors", meaning the user account or IP address that performed the edit, logged action, and so on. Instead of having user ID and name fields in each revision (rev_user+rev_user_text), log entry (log_user+log_user_text), and so on, we're storing the ID and name in a central "actor" table and referring to them by the actor ID from other tables (log_actor and so on).
We've been writing to the new fields and tables since mid-December 2018, and have back-populated them for old revisions, log
entries, and so on. We're about to start changing Wikimedia's production wikis to start reading the new fields instead of the old.
For the most part wiki users shouldn't notice any changes, however
if you notice something being newly slow or incorrectly displaying the user, please let me know.
For users
of the Data Services replicas, such as Toolforge, the views do still
include the old columns and they will be simulated even after MediaWiki stops writing them. But, for the non-compat views, this will change in the future as it recently did for the comment columns, so you may want to begin your migration process soon rather than waiting.
MediaWiki
developers should make sure code accessing user fields makes use of
the ActorMigration class that was introduced in MediaWiki 1.31.
--
Brad Jorsch (Anomie)
Senior Software Engineer
Wikimedia Foundation