The following schema changes should be applied to the revision and archive table in production, at DBA's discretion:
* Drop rev_text_id, rev_content_model, and rev_content_format that MCR obsoleted.
* Drop ar_text_id, ar_content_model, and ar_content_format that MCR obsoleted.
* Replace rev_comment with rev_comment_id.
* Replace rev_user and rev_user_text with rev_actor, plus associated index changes.
* The ALTER TABLES to run: https://gerrit.wikimedia.org/r/c/mediawiki/core/+/552339/19/maintenance/archives/patch-archive-MCR.sql https://gerrit.wikimedia.org/r/c/mediawiki/core/+/552339/19/maintenance/archives/patch-revision-actor-comment-MCR.sql https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/601713/4/maintenance/archives/patch-revision-actor-comment-MCR.sql
* Where to run those changes: all wikis
* When to run those changes: These changes can be applied at any time
* If the schema change is backwards compatible: The necessary conversion scripts have long ago been run. The fields that are being dropped have not been created for new installations for a while. The fields that are going to be dropped have been unused for several months now. Code for accessing them has been removed from core
* If the schema change has been tested already on some of the test/beta wikis. Usually, as a last test, change should be applied to testwiki first: The schema without these fields has been under testing in CI
* If it involves new columns or tables, if the data should be made available on the labs replicas: Some work needed on labs views: T238966#6118001
** The following new columns should be made available on labs and dumps:
*** rev_comment_id
*** rev_actor
Schema change progress:
[] s1
** [] eqiad progress T238966#6321602
** [x] codfw
[x] s2
** [x] eqiad progress T238966#6256330
** [x] codfw
[] s3 wikis to alter: T238966#6382076
*** [x] testwiki first
** [] eqiad
** [] codfw
[x] s4
** [x] eqiad progress (only the master is pending) T238966#6328792
** [x] codfw
[x] s5
** [x] eqiad progress T238966#6292637 (muswiki and mhwiktionary were altered separately T238966#6382059)
** [x] codfw
[x] s6
** [x] eqiad progress T238966#6148579
** [x] codfw
[x] s7
** [x] eqiad (only the master is pending) T238966#6358492
** [x] codfw
[] s8
** [] eqiad progress T238966#6376337
** [x] codfw
[x] Labswiki
[x] Labtestwiki (clouddb2001-dev)
[] Once the change is deployed, remove the columns from modules/role/files/mariadb/filtered_tables.txt to avoid having triggers on them