The actor and comment views on the wiki replicas are slowed by a need

to make subqueries against 8 other tables in order to determine 

which rows should and should not be visible on the replica service. With

recent changes to the replica view schema, this problem has become much more visible.

The WMCS team has deployed a set of specialized views of these two tables that

will allow individual queries to only be slowed by a single subquery against

a related target, eg. a query for an actor mentioned in the log_actor field of

the logging table could be made against actor_logging, which will only check against

logic in the actor table--not 7 other tables that aren't related to the query.

On the flip side the actor_logging view will only have rows that are exposed

in the logging table.

For more information, see: https://wikitech.wikimedia.org/wiki/News/Actor_storage_changes_on_the_Wiki_Replicas#The_actor_table_seems_really_slow--so_does_comment

If other documentation about the Wiki Replicas on wikitech needs updating related to this change, we would

 like your help finding it!  Please let us know on IRC, phab task, email or on wiki if you find things that need

 updating related to the actor and comment tables.  A Phabricator task is already open to update the MediaWiki

 documentation related (https://phabricator.wikimedia.org/T225007), but it is likely that there are bits around wikitech

 to update as well.