The `cupe_actor` column of the `cu_private_event` table was made nullable to prevent the need to acquire an actor ID for an IP address when temporary accounts are enabled. This was recommended over using a new table by @Ladsgroup in T359309#9615111.
# **ALTERs to run:** https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/CheckUser/+/0aafa1d1d990f6cabccf67e339ea46d360cdb158/schema/mysql/patch-cu_private_event-modify-cupe_actor-nullable.sql
# **Where to run those changes:** all
# **When to run those changes:** Ideally sooner than later as this blocks a testwiki deploy of temporary accounts
# **If the schema change is backwards compatible:** Yes.
# **If the schema change has been tested already on some of the test/beta wikis:** checkuser is not on beta cluster but has been deployed on a mwvagrant instance on https://checkuser-beta-wiki.wmcloud.org
# **If the data should be made available on the labs replicas and/or dumps:** Everything is private
[] s1 done except for dc-masters
[] s2 done except for dc-masters
[] s3 done except for dc-masters
[] s4 done except for dc-master eqiad
[x] s5
[] s6 done except for dc-master eqiad
[] s7 done except for dc-masters
[] s8 done except for dc-masters