As noticed in T104686
fr_user is unindexed
Wikis where this table is enabled: https://github.com/wikimedia/operations-mediawiki-config/blob/master/dblists/flaggedrevs.dblist
s1:
- enwiki
s2:
- eowiki
- fiwiki
- idwiki
- plwiki
- ptwiki
- trwiki
s3:
- alswiki
- bawiki (not enabled)
- bewiki
- bnwiki
- bswiki
- cawikinews
- cewiki
- ckbwiki
- de_labswikimedia (not enabled)
- dewikiquote
- dewiktionary
- elwikinews
- en_labswikimedia (not enabled)
- enwikibooks
- enwikinews
- eswikibooks (not enabled)
- eswikinews
- fawikinews
- flaggedrevs_labswikimedia (not enabled)
- frwikinews
- hewikisource
- hiwiki
- iawiki
- iswiktionary
- kawiki
- lawikisource
- mediawikiwiki (not enabled)
- mkwiki
- plwikisource
- plwiktionary
- ptwikibooks
- ptwikinews
- ptwikisource
- ruwikinews
- ruwikiquote
- ruwikisource
- ruwiktionary
- siwiki (not enabled)
- sqwiki
- srwikinews
- tawikinews
- test2wiki
- testwiki (not enabled)
- trwikiquote
- ukwiktionary
- vecwiki
- zh_classicalwiki
s5:
- dewiki
s6:
- frwiki
- ruwiki
s7:
- arwiki
- eswiki (not enabled)
- fawiki
- huwiki
- metawiki (not enabled)
- ukwiki
ALTER to run: ALTER TABLE /*$wgDBprefix*/flaggedrevs ADD INDEX (fr_user);