Once rows stop from coming in (see parent task), this will likely either solve or mitigate performance issues.
The rows affected seems to have rc_source = 'wb' (to be confirmed with wikidata team).
root@neodymium:~$ mysql -h db2073.codfw.wmnet commonswiki -e "SELECT COUNT(*) FROM recentchanges WHERE rc_source = 'wb'" +----------+ | COUNT(*) | +----------+ | 58075394 | +----------+ root@neodymium:~$ mysql -h db2073.codfw.wmnet commonswiki -e "SELECT COUNT(*) FROM recentchanges" +----------+ | COUNT(*) | +----------+ | 70880706 | +----------+
A backups should be done immediately before purging to avoid unaccounted effects.
Purging should be slow enough to not saturate replication or stole IOPS from main tasks.