From the checklist at https://wikitech.wikimedia.org/wiki/Schema_changes:
# **ALTERs to run:** https://gerrit.wikimedia.org/r/#/c/357892/14/maintenance/archives/patch-comment-table.sql (note there are some CREATEs in there too)
# **Where to run those changes:** all.dblist
# **When to run those changes:** No time constraint.
# **If the schema change is backwards compatible:** Yes. The new columns and tables won't be used until a feature flag is enabled.
# **If the schema change has been tested already on some of the test/beta wikis:** It appears to have been auto-deployed to Beta. Things seem to be working in some quick testing, and if anyone has complained about things breaking I haven't heard it.
# **if the data should be made available on the labs replicas and/or dumps:** Treatment of replicas and dumps are the same.
* All columns in the `comment` table can be made available without restriction. Rows must only be available if they are publicly referenced from one of the _id columns being added in this patch, as mentioned in T153333#3238701 and T153333#3238821. Extensions converted to have _id columns will eventually need to be added to that list. Note: From the MediaWiki side, this table should receive manly INSERTs, no UPDATEs, and DELETEs only due to potential maintenance.
* All columns in `revision_comment_temp` can be made available without restriction. Rows must only be available if the corresponding `revision` table row exists (join on `revcomment_rev = rev_id`) and has `(rev_deleted & 2) = 0`. Note: From the MediaWiki side, this table should receive INSERTs and DELETEs but no UPDATEs.
* All columns in `image_comment_temp` can be made available without restriction. Rows must only be available if the corresponding `image` table row exists (join on `imgcomment_name = img_name`). Note: From the MediaWiki side, this table should receive INSERTs and DELETEs but no UPDATEs.
* All the _id columns added to existing tables should be available under the same conditions as the corresponding column without the _id suffix. These seem to be:
** archive.ar_comment_id: Never available.
** ipblocks.ipb_reason_id: Always available (whenever the row itself is).
** oldimage.oi_description_id: Available when `(oi_deleted & 2) = 0`.
** filearchive.fa_description_id: Available when `(fa_deleted & 2) = 0`.
** filearchive.fa_deleted_reason_id: Always available.
** recentchanges.rc_comment_id: Available when `(rc_deleted & 2) = 0`.
** logging.log_comment_id: Available when `(log_deleted & 2) = 0`.
** protectedtitles.pt_reason_id: Always available.
* Progress:
** s1
*** [x] codfw
*** [x] eqiad T174569#3837301 (only the master pending)
** s2
*** [x] codfw
*** [x] eqiad T174569#3787775
** s3
*** [x] codfw
*** [x] eqiad T174569#3787775
** s4
*** [x] codfw
*** [x] eqiad T174569#3830446 (only the master pending)
** s5
*** [x] codfw
*** [] eqiad T174569#3889045
** s6
*** [x] codfw
*** [x] eqiad
** s7
*** [x] codfw
*** [x] eqiad T174569#3866346
** s8
*** [] codfw
*** [] eqiad
** [] labswiki (silver)
** [] Filter columns on: `modules/role/files/mariadb/filtered_tables.txt`